🐞 Unlink fragile dependency Docker image <-> tests

Previously we depended on the cunnie/fedora-golang-bosh image to have
the correct dependencies, and when it didn't it caused test failures.

This commit fixes that by downloading the dependencies before running
the tests (before running `ginkgo`)

Fixes:

```
xip/xip.go:21:2: no required module provides package golang.org/x/net/dns/dnsmessage; to add it:
	go get golang.org/x/net/dns/dnsmessage
```

.github/workflows/ci-tests.yml

@@ -14,5 +14,8 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Download dependencies
+        run: go mod download
+
       - name: Test
         run: ginkgo -r -p .