actions: pin to metomi-rose 2.0.x

* There have been no functional changes to Rose 2.1 yet so we are
  skipping release.
* Remove this pin when we are ready to build against Rose master
  again.

Author: oliver-sanders

.github/workflows/deploy.yml

@@ -87,6 +87,8 @@ jobs:
 
       - name: install libs to document
         uses: cylc/cylc-doc/.github/actions/install-libs@master
+        with:
+          metomi-rose-tag: '2.0.x'
 
       - name: create conda envs
         uses: ./docs/.github/actions/create-conda-envs

.github/workflows/nightly.yml

@@ -56,6 +56,8 @@ jobs:
 
       - name: install libs to document
         uses: ./docs/.github/actions/install-libs
+        with:
+          metomi-rose-tag: '2.0.x'
 
       - name: checkout gh-pages branch
         uses: actions/checkout@v3

.github/workflows/test.yml

@@ -64,6 +64,8 @@ jobs:
       - name: install libs to document (other branches)
         if: github.base_ref != '8.0.x'
         uses: ./.github/actions/install-libs
+        with:
+          metomi-rose-tag: '2.0.x'
 
       - name: install eslint
         run: |