DEV: Update the rubocop-discourse gem

This enables cops related to RSpec `subject`.

See https://github.com/discourse/rubocop-discourse/pull/32

spec/serializers/basic_group_serializer_spec.rb

@@ -1,16 +1,17 @@
 # frozen_string_literal: true
 
 RSpec.describe BasicGroupSerializer do
+  subject(:serializer) { described_class.new(group, scope: guardian, root: false) }
+
   let(:guardian) { Guardian.new }
   fab!(:group) { Fabricate(:group) }
-  subject { described_class.new(group, scope: guardian, root: false) }
 
   describe "#display_name" do
     describe "automatic group" do
       let(:group) { Group.find(1) }
 
       it "should include the display name" do
-        expect(subject.display_name).to eq(I18n.t("groups.default_names.admins"))
+        expect(serializer.display_name).to eq(I18n.t("groups.default_names.admins"))
       end
     end
 
@@ -18,22 +19,22 @@ RSpec.describe BasicGroupSerializer do
       fab!(:group) { Fabricate(:group) }
 
       it "should not include the display name" do
-        expect(subject.display_name).to eq(nil)
+        expect(serializer.display_name).to eq(nil)
       end
     end
   end
 
   describe "#bio_raw" do
-    fab!(:group) { Fabricate(:group, bio_raw: "testing :slightly_smiling_face:") }
-
-    subject do
+    subject(:serializer) do
       described_class.new(group, scope: guardian, root: false, owner_group_ids: [group.id])
     end
 
+    fab!(:group) { Fabricate(:group, bio_raw: "testing :slightly_smiling_face:") }
+
     describe "group owner" do
       it "should include bio_raw" do
-        expect(subject.as_json[:bio_raw]).to eq("testing :slightly_smiling_face:")
-        expect(subject.as_json[:bio_excerpt]).to start_with("testing <img")
+        expect(serializer.as_json[:bio_raw]).to eq("testing :slightly_smiling_face:")
+        expect(serializer.as_json[:bio_excerpt]).to start_with("testing <img")
       end
     end
   end
@@ -48,7 +49,7 @@ RSpec.describe BasicGroupSerializer do
 
       it "should be present" do
         Group.refresh_automatic_groups!
-        expect(subject.as_json[:has_messages]).to eq(true)
+        expect(serializer.as_json[:has_messages]).to eq(true)
       end
     end
 
@@ -59,7 +60,7 @@ RSpec.describe BasicGroupSerializer do
       before { group.add(user) }
 
       it "should be present" do
-        expect(subject.as_json[:has_messages]).to eq(true)
+        expect(serializer.as_json[:has_messages]).to eq(true)
       end
     end
 
@@ -67,7 +68,7 @@ RSpec.describe BasicGroupSerializer do
       let(:guardian) { Guardian.new(Fabricate(:user)) }
 
       it "should not be present" do
-        expect(subject.as_json[:has_messages]).to eq(nil)
+        expect(serializer.as_json[:has_messages]).to eq(nil)
       end
     end
   end
@@ -82,7 +83,7 @@ RSpec.describe BasicGroupSerializer do
       before { group.add(user) }
 
       it "should be true" do
-        expect(subject.as_json[:can_see_members]).to eq(true)
+        expect(serializer.as_json[:can_see_members]).to eq(true)
       end
     end
 
@@ -90,7 +91,7 @@ RSpec.describe BasicGroupSerializer do
       let(:guardian) { Guardian.new(Fabricate(:user)) }
 
       it "should be false" do
-        expect(subject.as_json[:can_see_members]).to eq(false)
+        expect(serializer.as_json[:can_see_members]).to eq(false)
       end
     end
   end