Is there some official mechanic in any class, feat, spell or magic item that allows someone to use strength for ranged attacks? As an example (but opposite) The Monk gets the feature Martial Arts which allows the Monk to use dexterity instead of strength.

All I could find that might work was one specific weapon from Waterdeep

There is a weapon in the Waterdeep: Dragon Heist module (p. 201) whose description includes (Spoiler Alert!):

Ziraj [the Hunter] ... carries an oversized longbow. This unique weapon can be used only by a Medium or larger creature that has a Strength of 18 or higher. The bow shoots oversized arrows that deal piercing damage equal to 2d6 + the wielder's Strength modifier. Its range is the same as an ordinary longbow.

Presumably this unique longbow would have its remaining stats be the same as other longbows: heavy, and two-handed, and has the ammunition property.

Whether this longbow lets you use Strength for attack or damage rolls is a bit unclear, so I have specifically asked about this in this Q/A: What modifiers are added to the attack and damage rolls of this unique longbow from Waterdeep?

This was the only method I could find to make a bow use Strength.

There are other features which allow you to use a different ability scores modifiers than usual but none of them would work for you. Some example features are listed below:

Finesse weapons let you use either but no bows are finesse weapons, as shown in this table (The only ranged finesse weapon at all is the dart):

When making an attack with a finesse weapon, you use your choice of your Strength or Dexterity modifier for the attack and damage rolls...

The Hexblade Warlock's Hex Warrior feature (XGtE, p. 55-56) would let you use Charisma, as it states:

When you attack with that weapon, you can use your Charisma modifier, instead of Strength or Dexterity, for the attack and damage rolls.

The Monk's Martial Arts feature can only replace strength with dexterity, but not the reverse as it states:

You can use Dexterity instead of Strength for the attack and damage rolls of your unarmed strikes and monk weapons.

The shillelagh spell is restricted to clubs and quarterstaves but states:

You can use your spellcasting ability instead of Strength for the attack and damage rolls of melee attacks using that weapon...

If you cannot get this NPC's unique longbow, your best alternative is probably just using javelins; out of all the thrown weapons that can use Strength, they allow you to attack from the farthest away (30/120).

There is nothing official that allows Str to be used with bow attacks.

None of the officially available sources (that I'm aware of) have a class feature, feat, spell, magic item or other effect that lets you add your Str modifier to bow attacks instead of Dex. If you want to be able to do this, you'll have to homebrew something like a bow with the finesse property.

The closest thing to what you're asking would be Thrown Weapons, which use the same modifier for their ranged attack as they do for their normal one (which is generally Str in the case of thrown melee weapons).

Since there's nothing to cite, the reason for this not being an available option is unclear, but if I were to hazard a guess I'd say that such a feature would potentially trivialise combat; a max-str melee class with a Longbow would be able to attack either in melee or at range at full capacity with no penalties.

As Medix pointed out, there is the NPC-owned Oversized Longbow from Waterdeep, but the discussion on that is undecided on whether you use Dex or Str for the attack roll since it only says to add your modifier to the damage.

Not a bow, but Thrown Weapons will work

As John Clifford mentions above, Thrown Weapons use the Strength modifier for attack rolls due to being melee weapons. While they're normally no bows (as requested by the question title), they do have the property of inherently being ranged attacks (which is in line with the question itself). This unique property of being melee weapons but a ranged attack is the most canon way to make use of Strength for ranged attacking.

As of a good option for such a thrown weapon, you could use any boomerang-styled item. With Princes of the Apocalypse, the Storm Boomerang is added and will likely work for you. In addition, D&D Beyond features a well-balanced "homebrew" mundane Boomerang that your GM will be likely to accept (although you might spend a while debating as you try to balance the missing stats). As mentioned in the comments, using Bonded Weapons can also be an option.

(Note: Strictly speaking, the mundane Boomerang mentioned above exists solely due to D&D Beyond's technical limitations, as a mundane weapon for the Storm Boomerang to be a magic version of; it is not intended as homebrew. However, that should have little impact on its usability.)