add conditional to run shell check

Author: LukasAud

.github/workflows/gem_ci.yml

@@ -24,11 +24,17 @@ on:
         required: false
         default: "ubuntu-latest"
         type: "string"
+      run_shellcheck:
+        description: "Run shellcheck on all bash files"
+        required: false
+        default: false
+        type: "boolean"
 
 jobs:
   shellcheck:
     name: "shellcheck"
     runs-on: ${{ inputs.runs_on }}
+    if: ${{ inputs.run_shellcheck }}
     steps:
       - uses: actions/checkout@v4
       - name: shellcheck