Fix typo in documentation production job for master

Author: alexandrebouthinon

.github/workflows/push_master.workflow.yml

@@ -131,7 +131,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
         with:
-        fetch-depth: 0
+          fetch-depth: 0
       - name: Extract references from context
         shell: bash
         id: extract-refs