rpc: fix gofmt error

Both gofmt 1.11.1 and 1.12.1 flagged this as a formatting error.

Author: pohly

rpc/common_test.go

@@ -241,7 +241,7 @@ func TestGetPluginCapabilities(t *testing.T) {
 			defer os.RemoveAll(tmp)
 			identity := &fakeIdentityServer{
 				getPluginCapabilitiesResponse: test.output,
-				err: injectedErr,
+				err:                           injectedErr,
 			}
 			addr, stopServer := startServer(t, tmp, identity, nil)
 			defer func() {
@@ -366,7 +366,7 @@ func TestGetControllerCapabilities(t *testing.T) {
 			defer os.RemoveAll(tmp)
 			controller := &fakeControllerServer{
 				controllerGetCapabilitiesResponse: test.output,
-				err: injectedErr,
+				err:                               injectedErr,
 			}
 			addr, stopServer := startServer(t, tmp, nil, controller)
 			defer func() {