Add codeclimate bundler-audit, fixme, and rubocop plugins

.codeclimate.yml

@@ -0,0 +1,41 @@
+version: "2"
+exclude_patterns:
+  - "sig/**/*"
+checks:
+  argument-count:
+    config:
+      threshold: 4
+  complex-logic:
+    config:
+      threshold: 4
+  file-lines:
+    config:
+      threshold: 250
+  method-complexity:
+    config:
+      threshold: 9
+  method-count:
+    config:
+      threshold: 20
+  method-lines:
+    config:
+      threshold: 25
+  nested-control-flow:
+    config:
+      threshold: 4
+  return-statements:
+    config:
+      threshold: 4
+plugins:
+  rubocop:
+    enabled: true
+    channel: 'rubocop-1-24-1'
+  bundler-audit:
+    enabled: true
+  fixme:
+    enabled: true
+    config:
+      strings:
+        - FIXME
+        - BUG
+        - CUSTOM