Fix some issues pointed out by zizmor. (#63)

Author: felixfontein

.github/workflows/nox.yml

@@ -51,6 +51,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           path: antsibull-docs-parser
+          persist-credentials: false
       - name: Install extra packages
         if: "matrix.packages != ''"
         run: |
@@ -89,6 +90,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           path: antsibull-docs-parser
+          persist-credentials: false
       - name: Setup nox
         uses: wntrblm/[email protected]  # DO NOT UPDATE THIS! Newer versions do not work with Python 3.6
         with: