ci(publish): fix tag and publish job to use python 3.8

[a-dubs]

Fixes: GH-458 (#458)

Here is the workflow run that passed using the new changes:
https://github.com/canonical/pycloudlib/actions/runs/12872046199/job/35886676346

Here was the patch that allowed the above changes to work:

diff --git a/.github/workflows/tag_and_publish.yaml b/.github/workflows/tag_and_publish.yaml
index 96569ae..4186032 100644
--- a/.github/workflows/tag_and_publish.yaml
+++ b/.github/workflows/tag_and_publish.yaml
@@ -3,6 +3,7 @@ on:
   push:
     branches:
       - main
+      - GH-458-fix-publish-job
 
 concurrency: ${{ github.ref }}
 
@@ -18,9 +19,9 @@ jobs:
         id: tag-release
         run: |
           version=$(cat VERSION)
-          git tag $version
-          git push origin $version
-          echo "version=$version" >> $GITHUB_OUTPUT
+          # git tag $version
+          # git push origin $version
+          # echo "version=$version" >> $GITHUB_OUTPUT
   publish-release:
     needs: tag-release
     runs-on: ubuntu-latest
@@ -29,10 +30,10 @@ jobs:
         uses: actions/checkout@v3
         with:
           ref: ${{ needs.tag-release.outputs.version}}
-      - name: Set up Python 3.7
+      - name: Set up Python 3.8
         uses: actions/setup-python@v3
         with:
-          python-version: "3.7"
+          python-version: "3.8"
       - name: Install pypa/build
         run: python -m pip install build --user
       - name: Build sdist and wheel

As you can see, i had to temporarily disable the git commands run in the tag-release step and then also temporarily add this branch as an allowed branch to trigger the workflow action.

[TheRealFalcon]

Needs a version bump, but otherwise LGTM

[a-dubs]

@TheRealFalcon bumped!

[TheRealFalcon]

Thanks!