gnome3.evolution-data-server: Re-add GNOME Online Accounts support

In #26879, GNOME Online Accounts support was removed resulting in
repeated authentication prompts for users relying on services like
Google Calendar.

This commit removes the build flag that disabled the support.

pkgs/desktops/gnome-3/core/evolution-data-server/default.nix

@@ -16,7 +16,7 @@ stdenv.mkDerivation rec {
   propagatedBuildInputs = [ libsecret nss nspr libical db ];
 
   # uoa irrelevant for now
-  cmakeFlags = [ "-DENABLE_UOA=OFF" "-DENABLE_GOA=OFF" ]
+  cmakeFlags = [ "-DENABLE_UOA=OFF" ]
                    ++ stdenv.lib.optionals valaSupport [
                      "-DENABLE_VALA_BINDINGS=ON" "-DENABLE_INTROSPECTION=ON"
                      "-DCMAKE_SKIP_BUILD_RPATH=OFF" ];