Try auto-labeling a few more things

.github/labeler.yml

@@ -2,5 +2,22 @@
   - doc/manual/*
   - src/nix/**/*.md
 
+"store":
+  - src/libstore/store-api.*
+  - src/libstore/*-store.*
+
+"fetching":
+  - src/libfetchers/**/*
+
+"repl":
+  - src/libcmd/repl.*
+  - src/nix/repl.*
+
+"new-cli":
+  - src/nix/**/*
+
 "tests":
+  # Unit tests
+  - src/*/tests/**/*
+  # Functional and integration tests
   - tests/**/*