fix: accepts uppercase values in mongoose.isValidObjectId

[foxadb]

Summary

ObjectId are case-insensitives in MongoDB as long as the value is hexadecimal.

mongoose.isValidObjectId function should consider uppercase ObjectId as valid.

Example

Adding the two following assertions to the test suite:

assert.ok(mongoose.isValidObjectId('5f5c2d56f6e911019ec2acdc')); // passing before and after change
assert.ok(mongoose.isValidObjectId('608DE01F32B6A93BBA314159')); // passing only after change

[vkarpov15]

Thanks 👍