Add golangci-lint config

.golangci.yml

@@ -0,0 +1,9 @@
+linters:
+  enable-all: true
+
+linters-settings:
+  exhaustive:
+    # indicates that switch statements are to be considered exhaustive if a
+    # 'default' case is present, even if all enum members aren't listed in the
+    # switch
+    default-signifies-exhaustive: true