Update the release build yaml with the latest versions (#757)

Author: pwshBot

.vsts-ci/releasebuild.yml

@@ -2,11 +2,11 @@ name: s_$(stableReleaseTag)_p_$(previewReleaseTag)_l_$(ltsReleaseTag)$(Rev:_rr)
 
 parameters:
   - name: 'previewReleaseTag'
-    default: 'v7.4.0-preview.3'
+    default: 'v7.4.0-preview.4'
   - name: 'ltsReleaseTag'
-    default: 'v7.2.11'
+    default: 'v7.2.12'
   - name: 'stableReleaseTag'
-    default: 'v7.3.4'
+    default: 'v7.3.5'
 
 resources:
 - repo: self