fix(docker): fix nginx .gz match against cgit snapshots

This only deals with .gz files in the root of the request_uri
and now more. That is: /packages.gz goes through the nginx regex,
but now /cgit/.../snapshot/package.tar.gz is served by the cgit
block.

Signed-off-by: Kevin Morris <kevr@0cost.org>

docker/config/nginx.conf

@@ -94,7 +94,7 @@ http {
         ssl_certificate /etc/ssl/certs/web.cert.pem;
         ssl_certificate_key /etc/ssl/private/web.key.pem;
 
-        location ~ ^/.*\.gz$ {
+        location ~ ^/[^\/]+\.gz$ {
             # Override mime type to text/plain.
             types { text/plain gz; }
             default_type text/plain;