pre-commit: add hugo-version-check hook

.pre-commit-config.yaml

@@ -9,6 +9,20 @@ repos:
         exclude: .drone.yml  # drone's yaml is somewhat strange sometimes
   - repo: local
     hooks:
+      - id: hugo-version-check
+        name: hugo version check
+        entry: |
+          bash -c "
+            files='.drone.yml Dockerfile'
+            count=$(grep -oE '( |hugo-v)[0-9].[0-9].[0-9].[0-9]' $files | cut -d':' -f2 | sed -e 's/^ *//g' -e 's/hugo-v//g' | uniq | wc -l)
+            if [ $count -gt 1 ]; then
+              echo hugo versions inconsistent:
+              grep -noE --color=always '( |hugo-v)[0-9].[0-9].[0-9].[0-9]' $files
+              exit 1
+            fi
+          "
+        language: system
+        pass_filenames: false
       - id: check-compose-file
         name: check compose file
         language: system