Pin HedgeDoc to major version 1

From https://docs.hedgedoc.org/setup/getting-started/#upgrading-hedgedoc

> HedgeDoc follows [Semantic Versioning](https://semver.org/).
> This means that minor and patch releases should not introduce
> user-facing backwards-incompatible changes.

roles/docker/tasks/services/hedgedoc.yml

@@ -34,7 +34,7 @@
             - "{{ hedgedoc.volume_folder }}/db:/var/lib/postgresql/data"
         
         app:
-          image: quay.io/hedgedoc/hedgedoc:1.9.0
+          image: quay.io/hedgedoc/hedgedoc:1
           environment:
             CMD_DB_URL: "postgres://codimd:{{ postgres_passwords.hedgedoc }}@hedgedoc_database_1:5432/codimd"
             CMD_DOMAIN: "{{ hedgedoc.domain }}"
@@ -63,4 +63,4 @@
       networks: 
         hedgedoc:
         external_services:
-          external: true
+          external: true