ci: avoid GH runner bug about workspaces

see issue actions/checkout#785

Author: pthierry-ledger

action.yaml

@@ -15,6 +15,10 @@ inputs:
     description:  'compiler version (this may depends on the compiler provider)'
     type: string
     required: true
+  workspace:
+    description: 'current workspace path value (see GH checkout issue #785'
+    type: string
+    required: true
 
 runs:
   using: 'composite'
@@ -36,5 +40,5 @@ runs:
     - name: Link toolchain dir to predictable path in container
       run: |
         source=$(dirname $TOOLCHAIN_PATH)
-        ln -s $source ${{ github.workspace}}/${{ inputs.triple }}
+        ln -s $source ${{ inputs.workspace }}/${{ inputs.triple }}
       shell: bash