Allow unauthenticated users to modify L-*, PG-* and -Z* labels

Author: fmease

triagebot.toml

@@ -9,11 +9,14 @@ allow-unauthenticated = [
     "E-*",
     "F-*",
     "I-*",
+    "L-*",
     "NLL-*",
     "O-*",
+    "PG-*",
     "S-*",
     "T-*",
     "WG-*",
+    "-Z*",
     "beta-nominated",
     "const-hack",
     "llvm-*",