CI: Test (remove no-verify; use /guix-builder/ ca-cert path)

I expect this to fail.

.gitea/workflows/main.yaml

@@ -19,9 +19,9 @@ jobs:
         run: git --version
       - name:
         env:
-          GIT_SSL_NO_VERIFY: true
           GIT_CURL_VERBOSE: 1
           GIT_TRACE: 1
+          GIT_SSL_CAINFO: /guix-builder/etc/ssl/certs/ca-certificates.crt
         run: git clone https://git.home.rekahsoft.ca/${{ gitea.repository }}
       - name: Check out repository code
         uses: https://github.com/actions/checkout@v3