Update Dockerfile to fix #7529

[MatthiasJobst]

Add --noproxy for localhost to prevent from using a proxy for this request

Describe the pull request

This PR fixes #7529.

When the environment variables HTTP_PROXY and/or HTTPS_PROXY are set, the routing even for localhost goes through the proxy. In cases where the docker image uses a port redirection this request fails.
When accessing itself as a host a proxy is not really needed so this is disabled in the HEALTHCHECK.

Link to the issue: #7529

Checklist

• I agree to follow the Code of Conduct by submitting this pull request.
• I have read and acknowledge the Contributing guide.
• I have added test cases to cover the new code or have provided the test plan.

Test plan

This fix can be verified by starting a docker container with the following additional parameters: -e HTTP_PROXY=host.docker.internal -e HTTPS_PROXY=host.docker.internal. When this fix is not present a docker inspect or a docker ps will show the container as unhealthy. With this fix the container is healthy.

A command for verification could look like this:

docker run -d -e HTTP_PROXY=host.docker.internal -e HTTPS_PROXY=host.docker.internal --name gogs_test gogs/gogs:latest

docker ps gogs_test