use synapse v1.12.0 as default and add min twisted package version

defaults/main.yml

@@ -1,5 +1,5 @@
 ---
-matrix_version: "1.2.1"
+matrix_version: "1.12.0"
 
 matrix_user: matrix
 matrix_user_home: "/home/{{ matrix_user }}"

tasks/install.yml

@@ -25,6 +25,7 @@
         - pip
         - setuptools
         - "psycopg2~=2.7.0"
+        - "Twisted>=20.3.0"
 
     - name: Install Synapse in virtualenv
       pip: