Bump version to v0.19 (#230)

Author: qinsoon

CHANGELOG.md

@@ -1,3 +1,22 @@
+0.19.0 (2023-08-18)
+===
+
+## What's Changed
+* Rename alloc bit to valid object bit (VO bit) by @wks in https://github.com/mmtk/mmtk-openjdk/pull/214
+* Fix invalid register values in `arraycopy_epilogue` barrier by @wenyuzhao in https://github.com/mmtk/mmtk-openjdk/pull/216
+* Remove deprecated const. by @wks in https://github.com/mmtk/mmtk-openjdk/pull/217
+* Update MMTk core PR #817 (alternative approach) by @wks in https://github.com/mmtk/mmtk-openjdk/pull/220
+* Update to mmtk-core PR #838 by @qinsoon in https://github.com/mmtk/mmtk-openjdk/pull/221
+* Rename ambiguous `scan_thread_root{,s}` functions by @k-sareen in https://github.com/mmtk/mmtk-openjdk/pull/222
+* Update to MMTk core PR #875 by @qinsoon in https://github.com/mmtk/mmtk-openjdk/pull/225
+* Show the version after cd by @wks in https://github.com/mmtk/mmtk-openjdk/pull/227
+* Add features for genimmix and stickyimmix by @qinsoon in https://github.com/mmtk/mmtk-openjdk/pull/228
+* Pass hotspot command line flags to mmtk-core by @wenyuzhao in https://github.com/mmtk/mmtk-openjdk/pull/229
+* Fix unaligned edge access by @wks in https://github.com/mmtk/mmtk-openjdk/pull/232
+
+**Full Changelog**: https://github.com/mmtk/mmtk-openjdk/compare/v0.18.0...v0.19.0
+
+
 0.18.0 (2023-04-03)
 ===