Set urllib3 to 1.26.15

[Safewaan]

Implementation description

401s were being thrown (for me) on all endpoints because of this issue. The fix was to set urllib3 to 1.26.15.

Steps to test

1. Verify endpoints still work

What should reviewers focus on?

Checklist

• My PR name is descriptive and in imperative tense
• My commit messages are descriptive and in imperative tense. My commits are atomic and trivial commits are squashed or fixup'd into non-trivial commits
• I have run the appropriate linter(s)
• I have requested a review from the PL, as well as other devs who have background knowledge on this PR or who will be building on top of this PR
• If I have made API changes, I have updated the REST API Docs
• IF I have made changes to the db/models, I have updated the Data Models Page
• I have updated other Docs as needed