Dockerfile: Support socat use cases (#13208)

* Dockerfile: Support socat use cases

In some contexts it is necessary to provide access to Gitea via TCP ports and unix sockets.
Gitea (`gitea web`) can be configured to listen for connections via unix-socket or TCP port, but not both.
When Gitea is installed to the host this limitation can be worked around by installing socat on the host.
When running Gitea from a container this limitation cannot be workaround.

Add socat to Gitea container.

* Removed version

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

Dockerfile

@@ -37,6 +37,7 @@ RUN apk --no-cache add \
     openssh \
     s6 \
     sqlite \
+    socat \
     su-exec \
     gnupg