fix: pin poetry to version used in CI

Pin poetry to version 1.3.2, which is currently used in CI, to ensure
that all builds are consistent. Also, fix typo in `doc` group name.

Change-Id: Id0c1aa88ac7ffcc241a51c693570e87abacf7ebc
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>

.readthedocs.yaml

@@ -17,10 +17,10 @@ build:
     - plantuml
   jobs:
     post_create_environment:
-      - pip install poetry
+      - pip install poetry=="1.3.2"
       - poetry config virtualenvs.create false
     post_install:
-      - poetry install --with docs
+      - poetry install --with doc
 
 sphinx:
   configuration: docs/conf.py