ci: FIX passing os as an array

.github/workflows/build.yml

@@ -23,7 +23,8 @@ on:
 jobs:
   build:
     name: ${{ inputs.name }}
-    runs-on: ${{ inputs.os }}
+    runs-on:
+      - ${{ inputs.os }}
     timeout-minutes: ${{ inputs.timeout }}
     steps:
       - name: Free disk space

.github/workflows/check.yml

@@ -37,8 +37,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix: ${{ fromJSON(needs.prepare.outputs.matrix) }}
+    secrets: inherit
     with:
       name: ${{ matrix.name }} (${{ matrix.system }})
       system: ${{ matrix.system }}
-      os: ${{ matrix.os }}
+      os: ${{ join( matrix.os, ' ' ) }} # FIXME: os is an array!
       attr: ${{ matrix.attr }}