chore: remove Python 3.9 support

Author: stanislaw

.github/workflows/ci-linux-ubuntu-latest.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         python-version: [
-          "3.9", "3.12"
+          "3.10", "3.14"
         ]
 
     steps:

.github/workflows/ci-mac.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         python-version: [
-          "3.9", "3.13"
+          "3.10", "3.13"
         ]
 
     steps:

tasks.py

@@ -151,7 +151,7 @@ def lint_mypy(context):
                 --disable-error-code=misc
                 --cache-dir=build/mypy
                 --strict
-                --python-version=3.9
+                --python-version=3.10
         """,
     )