ci: README build badge no longer shows failing when a queued main build is cancelled (#16054)

.github/workflows/main_build_status.yml

@@ -0,0 +1,27 @@
+# Reports the newest push build of main that was not cancelled, for the README badge.
+name: Main build status
+
+on:
+  workflow_run:
+    workflows: ["Build all"]
+    types: [completed]
+    branches: [main]
+
+permissions:
+  actions: read
+
+jobs:
+  status:
+    if: github.repository == 'OrcaSlicer/OrcaSlicer'
+    runs-on: ubuntu-latest
+    steps:
+      - env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          for attempt in 1 2 3; do
+            conclusion=$(gh api "repos/${{ github.repository }}/actions/workflows/build_all.yml/runs?branch=main&event=push&status=completed&per_page=100" \
+              --jq '[.workflow_runs[] | select(.conclusion != "cancelled")][0].conclusion') && break
+            sleep 10
+          done
+          echo "Latest finished push build of main: $conclusion"
+          [ "$conclusion" = success ]

README.md

@@ -6,7 +6,7 @@
 
 <a href="https://trendshift.io/repositories/15552" target="_blank"><img src="https://trendshift.io/api/badge/repositories/15552" alt="OrcaSlicer%2FOrcaSlicer | Trendshift" style="width: 250px; height: 55px;" width="250" height="55"/></a>
 
-[![GitHub Repo stars](https://img.shields.io/github/stars/OrcaSlicer/OrcaSlicer)](https://github.com/OrcaSlicer/OrcaSlicer/stargazers) [![Build all](https://github.com/OrcaSlicer/OrcaSlicer/actions/workflows/build_all.yml/badge.svg?branch=main)](https://github.com/OrcaSlicer/OrcaSlicer/actions/workflows/build_all.yml)
+[![GitHub Repo stars](https://img.shields.io/github/stars/OrcaSlicer/OrcaSlicer)](https://github.com/OrcaSlicer/OrcaSlicer/stargazers) [![Build all](https://img.shields.io/github/actions/workflow/status/OrcaSlicer/OrcaSlicer/main_build_status.yml?label=Build%20all)](https://github.com/OrcaSlicer/OrcaSlicer/actions/workflows/build_all.yml)
 
 OrcaSlicer: an open source Next-Gen Slicing Software for Precision 3D Prints.  
 Optimize your prints with ultra-fast slicing, intelligent support generation, and seamless printer compatibility—engineered for perfection.