revert github/codecov pinning, add version comments

GitHubs own actions are fully trusted, let's keep the paranoia on a reasonable level. This includes codecov too.
All other third party actions are pinned, but with a comment about what version they were tagged with before pinning.

.github/workflows/codeql-analysis.yml

@@ -31,7 +31,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8
+      uses: actions/checkout@v3
       with:
         # We must fetch at least the immediate parents so that if this is
         # a pull request then we can checkout the head.
@@ -44,7 +44,7 @@ jobs:
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@807578363a7869ca324a79039e6db9c843e0e100
+      uses: github/codeql-action/init@v2
       with:
         languages: ${{ matrix.language }}
         # If you wish to specify custom queries, you can do so here or in a config file.
@@ -55,7 +55,7 @@ jobs:
     # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
     # If this step fails, then you should remove it and run the build manually (see below)
     - name: Autobuild
-      uses: github/codeql-action/autobuild@807578363a7869ca324a79039e6db9c843e0e100
+      uses: github/codeql-action/autobuild@v2
 
     # ℹ️ Command-line programs to run using the OS shell.
     # 📚 https://git.io/JvXDl
@@ -69,4 +69,4 @@ jobs:
     #   make release
 
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@807578363a7869ca324a79039e6db9c843e0e100
+      uses: github/codeql-action/analyze@v2