ga: add a pylint check to avoid adding open calls without encoding= (#48099)

.github/workflows/valid-style.yml

@@ -13,8 +13,7 @@ concurrency:
 
 
 jobs:
-  # Validate that the code can be run on all the Python versions
-  # supported by Spack
+  # Validate that the code can be run on all the Python versions supported by Spack
   validate:
     runs-on: ubuntu-latest
     steps:
@@ -87,6 +86,7 @@ jobs:
           spack -d bootstrap now --dev
           spack -d style -t black
           spack unit-test -V
+  # Check we don't make the situation with circular imports worse
   import-check:
     runs-on: ubuntu-latest
     steps:
@@ -146,3 +146,21 @@ jobs:
         else
           printf '\033[1;32mImport check passed: %s <= %s\033[0m\n' "$edges_after" "$edges_before"
         fi
+
+  # Further style checks from pylint
+  pylint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-python@0b93645e9fea7318ecaed2b359559ac225c90a2b
+        with:
+          python-version: '3.13'
+          cache: 'pip'
+      - name: Install Python packages
+        run: |
+          pip install --upgrade pip setuptools pylint
+      - name: Pylint (Spack Core)
+        run: |
+          pylint -j 4 --disable=all --enable=unspecified-encoding --ignore-paths=lib/spack/external lib