Bump CI actions off the deprecated Node 20 runtime (#105)

checkout v4.4.0 -> v5.1.0 and setup-python v5.6.0 -> v6.3.0, SHA-pinned
as before. actionlint is already at the latest v1.7.12.

Closes #4

Claude-Session: https://claude.ai/code/session_01Aw4Pi9QbDEHbLML8LrJ2Fc

Co-authored-by: Blazer135 <56236007+Blazer135@users.noreply.github.com>

Author: AngriestBird

.github/workflows/ci.yml

@@ -18,12 +18,12 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      # actions/checkout v4.4.0
-      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262
+      # actions/checkout v5.1.0
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09
         with:
           persist-credentials: false
-      # actions/setup-python v5.6.0
-      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065
+      # actions/setup-python v6.3.0
+      - uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1
         with:
           python-version: "3.12"
           cache: pip
@@ -43,12 +43,12 @@ jobs:
         python-version: ["3.10", "3.14"]
     runs-on: ubuntu-latest
     steps:
-      # actions/checkout v4.4.0
-      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262
+      # actions/checkout v5.1.0
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09
         with:
           persist-credentials: false
-      # actions/setup-python v5.6.0
-      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065
+      # actions/setup-python v6.3.0
+      - uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1
         with:
           python-version: ${{ matrix.python-version }}
           cache: pip
@@ -60,13 +60,13 @@ jobs:
     if: github.event_name == 'pull_request'
     runs-on: ubuntu-latest
     steps:
-      # actions/checkout v4.4.0
-      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262
+      # actions/checkout v5.1.0
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09
         with:
           persist-credentials: false
           fetch-depth: 0
-      # actions/setup-python v5.6.0
-      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065
+      # actions/setup-python v6.3.0
+      - uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1
         with:
           python-version: "3.12"
           cache: pip