Update changelog and version after v1.0.10

CHANGELOG.md

@@ -1,5 +1,9 @@
 # CodeQL Action and CodeQL Runner Changelog
 
+## [UNRELEASED]
+
+No user facing changes.
+
 ## 1.0.10 - 03 Aug 2021
 
 - Fix an issue where a summary of diagnostics information from CodeQL was not output to the logs of the `analyze` step of the Action. [#672](https://github.com/github/codeql-action/pull/672)