Drop dedicated CI job for NEWS fragment check

Why: This task is now handled as a part of pre-commit's checks.

.github/workflows/python-linters.yml

@@ -41,17 +41,3 @@ jobs:
       run: >-
         python -m tox
       env: ${{ matrix.env }}
-
-  news_format:
-    name: Check NEWS format
-    runs-on: ubuntu-18.04
-    steps:
-    - uses: actions/checkout@master
-    - name: Set up Python
-      uses: actions/setup-python@v1
-      with:
-        version: 3.7
-    - name: Install nox
-      run: pip install nox
-    - name: Check NEWS format
-      run: nox -s validate_news

noxfile.py

@@ -1,7 +1,6 @@
 """Release time helpers, executed using nox.
 """
 
-import glob
 import io
 import subprocess
 
@@ -31,18 +30,6 @@ def get_author_list():
     return sorted(authors, key=lambda x: x.lower())
 
 
-# -----------------------------------------------------------------------------
-# Ad-hoc commands
-# -----------------------------------------------------------------------------
-@nox.session
-def validate_news(session):
-    session.install("rstcheck")
-
-    news_files = sorted(glob.glob("news/*"))
-
-    session.run("rstcheck", *news_files)
-
-
 # -----------------------------------------------------------------------------
 # Commands used during the release process
 # -----------------------------------------------------------------------------