Read proxy from environment for the selfhosted client (#145)

Co-authored-by: Joshua Wright <19779568+joshw123@users.noreply.github.com>
Co-authored-by: David Collom <david.collom@jetstack.io>

pkg/client/selfhosted/selfhosted.go

@@ -130,6 +130,7 @@ func New(ctx context.Context, log *logrus.Entry, opts *Options) (*Client, error)
 
 		client.Client.Transport = &http.Transport{
 			TLSClientConfig: tlsConfig,
+			Proxy:           http.ProxyFromEnvironment,
 		}
 	}