Simplify upmerge workflow to single job with dynamic matrix

Author: Rafikooo

.github/workflows/upmerge_pr.yaml

@@ -20,19 +20,15 @@ permissions:
     pull-requests: write
 
 jobs:
-    # Scheduled runs or manual without inputs - use matrix
-    upmerge-matrix:
-        if: github.repository == 'Sylius/CmsPlugin' && !inputs.base_branch
+    upmerge:
         runs-on: ubuntu-latest
+        if: github.repository == 'Sylius/CmsPlugin'
         name: "Upmerge PR"
         timeout-minutes: 5
         strategy:
             fail-fast: false
             matrix:
-                include:
-                    -
-                        base_branch: "1.0"
-                        target_branch: "1.1"
+                include: ${{ inputs.base_branch && fromJson(format('[{"base_branch":"{0}","target_branch":"{1}"}]', inputs.base_branch, inputs.target_branch)) || fromJson('[{"base_branch":"1.0","target_branch":"1.1"}]') }}
 
         steps:
             -
@@ -46,23 +42,3 @@ jobs:
                     base_branch: ${{ matrix.base_branch }}
                     target_branch: ${{ matrix.target_branch }}
                     token: ${{ secrets.SYLIUS_BOT_PAT }}
-
-    # Manual with custom inputs
-    upmerge-custom:
-        if: github.repository == 'Sylius/CmsPlugin' && inputs.base_branch
-        runs-on: ubuntu-latest
-        name: "Upmerge PR (${{ inputs.base_branch }} -> ${{ inputs.target_branch }})"
-        timeout-minutes: 5
-
-        steps:
-            -
-                uses: actions/checkout@v4
-                with:
-                    ref: ${{ inputs.target_branch }}
-
-            -
-                uses: SyliusLabs/UpmergeAction@v1
-                with:
-                    base_branch: ${{ inputs.base_branch }}
-                    target_branch: ${{ inputs.target_branch }}
-                    token: ${{ secrets.SYLIUS_BOT_PAT }}