Add optional base_directory to run mypy

Author: cedelavergne-ledger

.github/workflows/reusable_python_checks.yml

@@ -23,6 +23,11 @@ on:
         required: false
         default: ''
         type: string
+      base_directory:
+        description: "The base directory to go before runing mypy"
+        required: false
+        default: ''
+        type: string
       setup_directory:
         description: "The directory containing the setup.cfg (if any)"
         required: false
@@ -96,4 +101,8 @@ jobs:
           fi
 
       - name: Mypy type checking
-        run: mypy ${{ inputs.src_directory }}
+        run: |
+          if [ -n "${{ inputs.base_directory }}" ]; then
+            cd ${{ inputs.base_directory }}
+          fi
+          mypy ${{ inputs.src_directory }}