chore(github-actions): pin reqstool/.github references to 1.0.0 (#44)

Replaces a mix of @main and @<sha> # main <date> with a single shape:
@<sha> # 1.0.0, against reqstool/.github's first tag.

@main is mutable, so CodeQL's actions/unpinned-tag flags it and any
change to the shared workflows reaches this repo with no review -- which
bit twice this week while the PyPI publish path was being fixed. A bare
tag would still be mutable; the sha-with-version-comment form satisfies
the pinning audits while letting Renovate track the digest and rewrite
the comment, so the pin does not rot.

Implements reqstool/.github#25.

Signed-off-by: Jimisola Laursen <jimisola@jimisola.com>

Author: jimisola

.github/workflows/check-semantic-pr.yml

@@ -10,4 +10,4 @@ permissions:
 
 jobs:
   check:
-    uses: reqstool/.github/.github/workflows/common-check-semantic-pr.yml@main
+    uses: reqstool/.github/.github/workflows/common-check-semantic-pr.yml@ef815eae0bca7160cdc714126cac73f76d638b39 # 1.0.0

.github/workflows/publish_gh_pages.yml

@@ -13,7 +13,7 @@ permissions:
 
 jobs:
   publish:
-    uses: reqstool/.github/.github/workflows/common-publish-to-github-pages.yml@main
+    uses: reqstool/.github/.github/workflows/common-publish-to-github-pages.yml@ef815eae0bca7160cdc714126cac73f76d638b39 # 1.0.0
     permissions:
       contents: read
       pages: write