GHA: rename unit-ro to unit_ro

Author: dmach

.github/workflows/tests.yaml

@@ -15,7 +15,7 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  unit-ro:
+  unit_ro:
     name: "unit - read only fixtures"
     runs-on: 'ubuntu-latest'
     strategy:
@@ -44,7 +44,7 @@ jobs:
 
   unit:
     name: "unit"
-    needs: unit-ro
+    needs: unit_ro
     runs-on: 'ubuntu-latest'
     strategy:
       fail-fast: false