[CI] it looks like git has to be inside container

... so that action/checkout@v2 could do a `git clone` instead of
downloading the repo archive.

ref: actions/checkout#175 (comment)

.github/workflows/ci.yml

@@ -8,12 +8,14 @@ jobs:
     container:
       image: perl:5.32
     steps:
+      - name: install dependencies
+        run: |
+          apt install -y git
+          cpanm --notest --quiet App::PerlNitpick
       - uses: actions/checkout@v2
       - uses: gugod/action-perlcritic@fun
         with:
           directory: "lib script t dev-bin"
-      - name: install perlnitpick
-        run: cpanm --notest --quiet App::PerlNitpick
       - name: run perlnitpick
         run: perlnitpick --inplace --rules=RemoveTrailingWhitespace,RemoveUnusedVariables,RemoveUnusedInclude,RemoveUnusedImport .
       - name: suggester