Define ruff version in the github actions file instead

Placing it in requirements.txt means the docker images try to install it
even though they don't need it.

.github/workflows/python-app.yml

@@ -9,6 +9,9 @@ on:
     pull_request:
         branches: [ main ]
 
+env:
+    RUFF_VERSION: 0.3.4
+
 jobs:
     build-baseline:
         runs-on: ubuntu-latest
@@ -32,7 +35,7 @@ jobs:
                     # Use the system-provided python3 instead of actions/setup-python@v4
                     python3 --version
                     python3 -m pip install --upgrade pip
-                    python3 -m pip install --upgrade pre-commit
+                    python3 -m pip install --upgrade pre-commit ruff==${{ env.RUFF_VERSION }}
                     python3 -m pip install -r requirements.txt
             -   name: Lint with flake8
                 run: flake8
@@ -54,7 +57,7 @@ jobs:
             -   name: Install dependencies
                 run: |
                     python -m pip install --upgrade pip
-                    pip install --upgrade pre-commit
+                    pip install --upgrade pre-commit ruff==${{ env.RUFF_VERSION }}
                     if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
             -   name: Lint with flake8
                 run: flake8

tests/requirements.txt

@@ -5,4 +5,3 @@ argcomplete>=2.0.0
 # Only needed for RISC-V FPGA boot -> not bundled
 pyserial>=3.5
 flake8
-ruff==0.3.4