Fix GHA Protoc Installation

The protobuf compiler that is being installed in GitHub Actions has a different
version than the library that is used by Karapace. To avoid further drift it is
necessary to ensure that they stay aligned automatically. This patch adds some
code to extract the actual Protobuf version from the `requirements.txt` file.

Note that this approach is going to break with newer Protobuf versions. This is
because Google decided to stop versioning all Protobuf dependencies alike.
However, newer versions of Python Protobuf do not require the Protobuf Compiler
to be installed anymore. Hence, if we upgrade, we can get rid of the Protobuf
Compiler installation entirely.

.github/workflows/tests.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.7, 3.8, 3.9, "3.10", "3.11"]
+        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
     steps:
     - uses: actions/checkout@v3
 
@@ -27,13 +27,17 @@ jobs:
     - name: Install dependencies
       run: python -m pip install -r requirements-dev.txt
 
-    - name: Install Protoc
+    - name: Extract Protobuf Version
+      id: protoc
+      run: pip freeze | grep -m1 '^protobuf==' | cut -d= -f3 | xargs printf 'version=%s' >>"$GITHUB_OUTPUT"
+
+    - name: Install Protobuf Compiler
       uses: arduino/setup-protoc@v1
       with:
-         version: '3.13.0'
+         version: ${{ steps.protoc.outputs.version }}
          repo-token: ${{ secrets.GITHUB_TOKEN }}
 
-    # needed by both unit and integation tests
+    # needed by both unit and integration tests
     - name: Generate version.py
       run: make karapace/version.py