Make mautrix-python-based bridges E2EE happier

Fixes a problem like this:
> File "/usr/lib/python3.8/site-packages/mautrix/bridge/e2ee.py", line 79, in __init__
> raise RuntimeError("Unsupported database scheme")

mautrix-python's e2ee.py module expects to find `postgres://` instead of
`postgresql://`.

roles/matrix-bridge-mautrix-facebook/defaults/main.yml

@@ -51,7 +51,7 @@ matrix_mautrix_facebook_database_hostname: 'matrix-postgres'
 matrix_mautrix_facebook_database_port: 5432
 matrix_mautrix_facebook_database_name: 'matrix_mautrix_facebook'
 
-matrix_mautrix_facebook_database_connection_string: 'postgresql://{{ matrix_mautrix_facebook_database_username }}:{{ matrix_mautrix_facebook_database_password }}@{{ matrix_mautrix_facebook_database_hostname }}:{{ matrix_mautrix_facebook_database_port }}/{{ matrix_mautrix_facebook_database_name }}'
+matrix_mautrix_facebook_database_connection_string: 'postgres://{{ matrix_mautrix_facebook_database_username }}:{{ matrix_mautrix_facebook_database_password }}@{{ matrix_mautrix_facebook_database_hostname }}:{{ matrix_mautrix_facebook_database_port }}/{{ matrix_mautrix_facebook_database_name }}'
 
 matrix_mautrix_facebook_appservice_database: "{{
 	{

roles/matrix-bridge-mautrix-hangouts/defaults/main.yml

@@ -58,7 +58,7 @@ matrix_mautrix_hangouts_database_hostname: 'matrix-postgres'
 matrix_mautrix_hangouts_database_port: 5432
 matrix_mautrix_hangouts_database_name: 'matrix_mautrix_hangouts'
 
-matrix_mautrix_hangouts_database_connection_string: 'postgresql://{{ matrix_mautrix_hangouts_database_username }}:{{ matrix_mautrix_hangouts_database_password }}@{{ matrix_mautrix_hangouts_database_hostname }}:{{ matrix_mautrix_hangouts_database_port }}/{{ matrix_mautrix_hangouts_database_name }}'
+matrix_mautrix_hangouts_database_connection_string: 'postgres://{{ matrix_mautrix_hangouts_database_username }}:{{ matrix_mautrix_hangouts_database_password }}@{{ matrix_mautrix_hangouts_database_hostname }}:{{ matrix_mautrix_hangouts_database_port }}/{{ matrix_mautrix_hangouts_database_name }}'
 
 matrix_mautrix_hangouts_appservice_database: "{{
 	{

roles/matrix-bridge-mautrix-telegram/defaults/main.yml

@@ -62,7 +62,7 @@ matrix_mautrix_telegram_database_hostname: 'matrix-postgres'
 matrix_mautrix_telegram_database_port: 5432
 matrix_mautrix_telegram_database_name: 'matrix_mautrix_telegram'
 
-matrix_mautrix_telegram_database_connection_string: 'postgresql://{{ matrix_mautrix_telegram_database_username }}:{{ matrix_mautrix_telegram_database_password }}@{{ matrix_mautrix_telegram_database_hostname }}:{{ matrix_mautrix_telegram_database_port }}/{{ matrix_mautrix_telegram_database_name }}'
+matrix_mautrix_telegram_database_connection_string: 'postgres://{{ matrix_mautrix_telegram_database_username }}:{{ matrix_mautrix_telegram_database_password }}@{{ matrix_mautrix_telegram_database_hostname }}:{{ matrix_mautrix_telegram_database_port }}/{{ matrix_mautrix_telegram_database_name }}'
 
 matrix_mautrix_telegram_appservice_database: "{{
 	{