GitHub workflows: abi-stable (0.10.y only): update abi reference tag

With the ABI change between 0.10.5 and 0.10.6, use 0.10.6 as reference
tag now.

Signed-off-by: Martin Wilck <mwilck@suse.com>

Author: mwilck

.github/workflows/abi-stable.yaml

@@ -12,21 +12,13 @@ on:
     branches:
       - 'stable-*'
   workflow_dispatch:
+env:
+  PARENT_TAG: "0.10.6"
 
 jobs:
   reference-abi:
     runs-on: ubuntu-24.04
     steps:
-      - name: get parent tag (push)
-        run: >
-          echo ${{ github.ref }} |
-          sed -E 's,refs/heads/stable-([0-9]\.[0-9]*)\.y,PARENT_TAG=\1.0,' >> $GITHUB_ENV
-        if: github.event_name == 'push'
-      - name: get parent tag (PR)
-        run: >
-          echo ${{ github.base_ref }} |
-          sed -E 's,stable-([0-9]\.[0-9]*)\.y,PARENT_TAG=\1.0,' >> $GITHUB_ENV
-        if: github.event_name == 'pull_request'
       - name: assert parent tag
         run: /bin/false
         if: env.PARENT_TAG == ''
@@ -71,16 +63,6 @@ jobs:
     runs-on: ubuntu-24.04
     needs: reference-abi
     steps:
-      - name: get parent tag (push)
-        run: >
-          echo ${{ github.ref }} |
-          sed -E 's,refs/heads/stable-([0-9]\.[0-9]*)\.y,PARENT_TAG=\1.0,' >> $GITHUB_ENV
-        if: github.event_name == 'push'
-      - name: get parent tag (PR)
-        run: >
-          echo ${{ github.base_ref }} |
-          sed -E 's,stable-([0-9]\.[0-9]*)\.y,PARENT_TAG=\1.0,' >> $GITHUB_ENV
-        if: github.event_name == 'pull_request'
       - name: assert parent tag
         run: /bin/false
         if: env.PARENT_TAG == ''