github-ci: use git cli command for netmap instead of action

This action hits API limits often, however our other uses of git clone
do not seem to, so try use git clone here instead of the github
action.

.github/workflows/builds.yml

@@ -2216,11 +2216,7 @@ jobs:
 
       - name: Checkout Netmap repository
         if: steps.netmap-cache.outputs.cache-hit != 'true'
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
-        with:
-          repository: luigirizzo/netmap
-          # gets cloned to $GITHUB_WORKSPACE/netmap/
-          path: netmap/
+        run: git clone --depth 1 https://github.com/luigirizzo/netmap
 
       - name: Save Netmap Cache
         if: steps.netmap-cache.outputs.cache-hit != 'true'