Update dependency dotnet-coverage to v18

Author: renovate[bot]

.config/dotnet-tools.json

@@ -38,7 +38,7 @@
             "rollForward": false
         },
         "dotnet-coverage": {
-            "version": "17.14.2",
+            "version": "18.7.0",
             "commands": ["dotnet-coverage"],
             "rollForward": false
         },