Update outdated `.items` syntax

spec/models/build_spec.rb

@@ -175,7 +175,7 @@ describe Build do
       before { build.trace = text }
       it { should include(text) }
-      it { should have_at_least(text.length).items }
+      it { expect(subject.length).to be >= text.length }
     end
   end

spec/models/commit_spec.rb

@@ -123,14 +123,14 @@ describe Commit do
   describe '#short_before_sha' do
     subject { commit.short_before_sha }
-    it { should have(8).items }
+    it { expect(subject.length).to eq 8 }
     it { commit.before_sha.should start_with(subject) }
   end
   describe '#short_sha' do
     subject { commit.short_sha }
-    it { should have(8).items }
+    it { expect(subject.length).to eq 8 }
     it { commit.sha.should start_with(subject) }
   end