Fix root lint command

Author: code-asher

package.json

@@ -20,7 +20,7 @@
     "test:all": "backstage-cli repo test --coverage",
     "test:e2e": "playwright test",
     "fix": "backstage-cli repo fix",
-    "lint": "backstage-cli repo lint --since origin/master",
+    "lint": "backstage-cli repo lint --since origin/main",
     "lint:all": "backstage-cli repo lint",
     "prettier:check": "prettier --check .",
     "new": "backstage-cli new --scope internal"