test: add an integration test for embedded runner cache (#889)

Adds a limited integration test in the runner which verifies that the embedded cache server starts up, can be written to by an action, and can be read by a subsequent action.  This is a solid base foundation for future nearly-end-to-end tests.

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  - [PR](https://code.forgejo.org/forgejo/runner/pulls/889): <!--number 889 --><!--line 0 --><!--description dGVzdDogYWRkIGFuIGludGVncmF0aW9uIHRlc3QgZm9yIGVtYmVkZGVkIHJ1bm5lciBjYWNoZQ==-->test: add an integration test for embedded runner cache<!--description-->
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Reviewed-on: https://code.forgejo.org/forgejo/runner/pulls/889
Reviewed-by: earl-warren <earl-warren@noreply.code.forgejo.org>
Co-authored-by: Mathieu Fenniak <mathieu@fenniak.net>
Co-committed-by: Mathieu Fenniak <mathieu@fenniak.net>

.forgejo/workflows/test.yml

@@ -149,6 +149,44 @@ jobs:
           go test ./act/container
           go test -timeout 30m ./act/runner/...
 
+  runner-integration-tests:
+    name: runner integration tests
+    if: vars.ROLE == 'forgejo-coding'
+    runs-on: lxc-bookworm
+    needs: [build-and-tests]
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+
+      - name: install docker
+        run: |
+          mkdir /etc/docker
+          cat > /etc/docker/daemon.json  <<EOF
+          {
+            "ipv6": true,
+            "experimental": true,
+            "ip6tables": true,
+            "fixed-cidr-v6": "fd05:d0ca:1::/64",
+            "default-address-pools": [
+              {
+                "base": "172.19.0.0/16",
+                "size": 24
+              },
+              {
+                "base": "fd05:d0ca:2::/104",
+                "size": 112
+              }
+            ]
+          }
+          EOF
+          apt --quiet install --yes -qq docker.io make
+
+      - run: make integration-test
+
   validate-mocks:
     name: validate mocks
     if: vars.ROLE == 'forgejo-coding'