Bump idna from 3.4 to 3.7 in /llvm/utils/git

Bumps [idna](https://github.com/kjd/idna) from 3.4 to 3.7.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](kjd/idna@v3.4...v3.7)

---
updated-dependencies:
- dependency-name: idna
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

llvm/utils/git/requirements.txt

@@ -16,7 +16,7 @@ gitdb==4.0.9
     # via gitpython
 gitpython==3.1.41
     # via -r requirements.txt.in
-idna==3.4
+idna==3.7
     # via requests
 pycparser==2.21
     # via cffi