Update changelog and version after v1.0.27

CHANGELOG.md

@@ -1,5 +1,9 @@
 # CodeQL Action and CodeQL Runner Changelog
 
+## [UNRELEASED]
+
+No user facing changes.
+
 ## 1.0.27 - 11 Jan 2022
 
 - The `analyze` and `upload-sarif` actions will now wait up to 2 minutes for processing to complete after they have uploaded the results so they can report any processing errors that occurred. This behavior can be disabled by setting the `wait-for-processing` action input to `"false"`.