BUG: Fixed merge between int64 uint64 and wrote test

[YKim0172]

• closes BUG: Merges erroneously match integer join keys between int64 and uint64 when using values >= 2**53 #56367
• [Tests added and passed]: test_merge.py
• All [code checks passed]

When you have two DataFrames, left and right, where left's key is of dtype int64 while right's key is of dtype uint64, and both of their values are >= 2**53, what used to happen was that calling left.merge(right) will cause a non empty result to be returned. However, we want the merge function to return nothing since we shouldn't be allowing the merge between DataFrames with different key dtypes.

The issue was that when you are working with values >= 253 and you have keys that are of dtype int64 and uint64, the "common dtype" gets resolved to float64 for both, so a (253) int64 and (2**53 + 1) uint64 is represented as the same float64 value.

[mroeschke]

As mentioned in #56367 (comment), this appears to already work so it would just need a test

[mroeschke]

Thanks for the pull request, but it appears to have gone stale. If interested in continuing, please merge in the main branch, address any review comments and/or failing tests, and we can reopen.