Add and apply RSpec/BeEq rubocop rule

This rule was added in rubocop-rspec 2.9.0. Once again, we were applying
it about 50% of the time.

spec/models/proposal_spec.rb

@@ -272,7 +272,7 @@ describe Proposal do
         tag_list = ["tag1", "tag2", "tag3", "tag4", "tag5", "tag6", "tag7"]
         proposal.update!(tag_list: tag_list)
 
-        expect(proposal.update_cached_votes).to eq(true)
+        expect(proposal.update_cached_votes).to be true
       end
     end
   end
@@ -846,8 +846,8 @@ describe Proposal do
     let!(:proposal2) { create(:proposal, :retired) }
 
     it "retired? is true" do
-      expect(proposal1.retired?).to eq false
-      expect(proposal2.retired?).to eq true
+      expect(proposal1.retired?).to be false
+      expect(proposal2.retired?).to be true
     end
 
     it "scope retired" do
@@ -864,8 +864,8 @@ describe Proposal do
     let!(:archived_proposal) { create(:proposal, :archived) }
 
     it "archived? is true only for proposals created more than n (configured months) ago" do
-      expect(new_proposal.archived?).to eq false
-      expect(archived_proposal.archived?).to eq true
+      expect(new_proposal.archived?).to be false
+      expect(archived_proposal.archived?).to be true
     end
 
     it "scope archived" do