ci: update type-checking mypy to 2.1.0 to match the fork base

Bump the mypy used by the static-analysis workflow from 1.14.1 to 2.1.0, the
version our mypyc fork is based on, so type-checking matches what the compiled
build sees.

mypy 2.1 requires the type-check target (tool.mypy python_version) to be 3.10+,
so it can no longer be rez's lowest supported runtime (3.8); set it to 3.10.

Regenerate mypy-baseline.txt against mypy 2.1.0 (the error set differs from
1.14.1: 594 -> 234 baselined entries). Verified the baseline keeps the mypy
workflow green (mypy | mypy-baseline filter reports no new errors).

Author: chadrik

.github/workflows/mypy.yaml

@@ -38,7 +38,7 @@ jobs:
 
       - name: Install Dependencies
         run: |
-          pip install mypy==1.14.1 mypy_baseline==0.7.1 types-setuptools
+          pip install mypy==2.1.0 mypy_baseline==0.7.1 types-setuptools
 
       - name: Run mypy
         run: >-