Update meson to 0.63.0

Reason: meson 0.63.0 provides a new feature which allows user to apply
diff file on a subproject. This gives user a flexibility to have code
changes in subprojects while running the unit test.

Reference: https://mesonbuild.com/Wrap-dependency-system-manual.html#diff-files

Tested: Locally ran unit test and confirmed that the subproject applied
the diff files correctly.

Signed-off-by: Michael Shen <gpgpgp@google.com>
Change-Id: Icb1ad03d28496120f5afe8010cfa3a3b855975c8
diff --git a/scripts/build-unit-test-docker b/scripts/build-unit-test-docker
index 1c50b63..ddb4a45 100755
--- a/scripts/build-unit-test-docker
+++ b/scripts/build-unit-test-docker
@@ -843,7 +843,7 @@
 RUN pip3 install inflection
 RUN pip3 install pycodestyle
 RUN pip3 install jsonschema
-RUN pip3 install meson==0.61.3
+RUN pip3 install meson==0.63.0
 RUN pip3 install protobuf
 RUN pip3 install codespell
 RUN pip3 install requests