Disable http2 for kaniko

Fix #7 (closed)

I.e. work around https://github.com/GoogleContainerTools/kaniko/issues/2751

gitlab-pipeline.dhall

@@ -49,6 +49,9 @@ let
         , DOCKER_TLS_CERTDIR = "/certs"
           -- See https://gitlab.haskell.org/ghc/ci-images/-/issues/3
         , container = "docker"
+          -- HTTP2 is extremely slow, so it is disabled.
+          -- https://gitlab.haskell.org/ghc/ci-images/-/issues/7
+        , GODEBUG = "http2client=0"
         }
       , needs = image.needs # [ "generate-dockerfiles" ]
       , dependencies = [ "generate-dockerfiles" ]