Mark mautrix-hangouts bridge as due-for-removal

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3863

docs/configuring-playbook-bridge-mautrix-hangouts.md

@@ -1,6 +1,6 @@
 # Setting up Mautrix Hangouts bridging (optional, deprecated)
 
-**Note**: This bridge has been deprecated in favor of [Google Chat bridge](https://github.com/mautrix/googlechat), which can be installed using [this playbook](configuring-playbook-bridge-mautrix-googlechat.md). Consider using that bridge instead of this one.
+💡 **Note**: This bridge has been deprecated in favor of [Google Chat bridge](https://github.com/mautrix/googlechat), which can be installed using [this playbook](configuring-playbook-bridge-mautrix-googlechat.md). Installing the mautrix-hangouts bridge is **no longer possible**. For now, this documentation page remains here for historical purposes.
 
 The playbook can install and configure [mautrix-hangouts](https://github.com/mautrix/hangouts) for you.
 

roles/custom/matrix-bridge-mautrix-hangouts/tasks/validate_config.yml

@@ -1,5 +1,18 @@
 ---
 
+- ansible.builtin.fail:
+    msg: |-
+      The Google Hangouts service was discontinued on November 1st, 2022.
+      The mautrix-hangouts bridge (which you have enabled via the `matrix_mautrix_hangouts_enabled` variable) will be removed from the playbook soon (in February 2025).
+
+      We suggest that you uninstall this bridge by:
+      1. Tweaking your `vars.yml` file - setting `matrix_mautrix_hangouts_enabled` to `false` or better yet removing all `matrix_mautrix_hangouts_*` variables
+      2. Re-running the playbook with the `setup-all` (e.g. `just setup-all`) or `setup-mautrix-hangouts` tag (e.g. `just run-tags setup-mautrix-hangouts`), so that uninstallation tasks will run.
+
+      In the future, an error will be raised for any `matrix_mautrix_hangouts_*` variables that the playbook detects in your `vars.yml` configuration file.
+
+      Also see: https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3863
+
 - name: Fail if required mautrix-hangouts settings not defined
   ansible.builtin.fail:
     msg: >-