deps: Remove Python 3.7 and 3.8 as supported runtimes

Author: rahul2393

.github/workflows/presubmit.yaml

@@ -17,7 +17,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: 3.8
+          python-version: 3.9
       - name: Install nox
         run: python -m pip install nox
       - name: Check formatting
@@ -27,7 +27,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
+        python: ["3.9", "3.10", "3.11", "3.12", "3.13"]
 
     steps:
       - name: Checkout code