docs(changelog): update link in changelog

In this file GitHub does not turn commit SHAs into links.
Remove the links from the changes and instead change the link of
the version to a comparison.

CHANGELOG.md

@@ -22,13 +22,13 @@ Initial release (on github)
 
 ### Added
 
-- add data query EventFields: b2d29389631c70adfa1e09c9026a4ba7d6b5ac1b
-- add data query ConfigFields: cf755fd55626201c29d5caf043e782a6e592e17f
-- add missing details on aggregation: 077a5d1302137559de0cc9597a5730bbdc263e31
+- add data query EventFields
+- add data query ConfigFields
+- add missing details on aggregation
 
 ### Changed
 
 - change generics usage to fix broken build (#6)
 
 [unreleased]: https://github.com/paulscherrerinstitute/databuffer-query-js/compare/v0.3.0...HEAD
-[0.3.0]: https://github.com/paulscherrerinstitute/databuffer-query-js/releases/v0.3.0
+[0.3.0]: https://github.com/paulscherrerinstitute/databuffer-query-js/compare/a3098f3b37d19c347a5ca98efbc46a7f61d179bd...v0.3.0