Use latest release tag v23.11 for c-lightning instead of master; update GitHub action versions

.github/workflows/main.yml

@@ -23,14 +23,14 @@ jobs:
         deprecated: [0]
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
-    - name: Checkout c-lightning@master
-      uses: actions/checkout@v3
+    - name: Checkout c-lightning@v23.11
+      uses: actions/checkout@v4
       with:
         repository: 'ElementsProject/lightning'
         path: 'lightning'
-        ref: 'master'
+        ref: 'v23.11'
         submodules: 'recursive'
         fetch-depth: 0  # Required for pyln versions to be recognized
 
@@ -80,7 +80,7 @@ jobs:
         sudo make install
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.python-version }}