fix: bad variable

Author: 0xItadaki

.github/workflows/coverage.yml

@@ -48,8 +48,8 @@ jobs:
       - name: Prepare cached base total coverage
         if: steps.cache-base.outputs.cache-hit != 'true'
         run: |
-          total-coverage=$(lcov --summary lcov.info 2>/dev/null | awk '/lines\.+:/ {print $2}' | tr -d '%')
-          echo "$total-coverage" > total-coverage.txt
+          total_coverage=$(lcov --summary lcov.info 2>/dev/null | awk '/lines\.+:/ {print $2}' | tr -d '%')
+          echo "$total_coverage" > total-coverage.txt
 
       - name: Export base coverage output
         id: export-base