Updated changelog.txt

Author: pcingola

changelog.txt

@@ -1,3 +1,7 @@
+Version 1.8.1
+    - Updated version.
+    - Added validation of VCF files in integration tests. Fixed flag InDelLikely name in expected file and duplicated Bias filter. Updated submodule.
+
 Version 1.8
     - add conda and usegalaxy badge
     - Updated submodule