Fix b-test issues

This commit fixes two issues:
  - run.sh fails if ccache is not available in the system. The fix
    is to ignore the return value of the which command.
  - there is a pip dependency conflict between yasha and Sphinx. The
    first depends on jinja<2.11 and the second on Jinja2>=2.3. The
    conflict is removed by upgrading yasha.
    This issue only affects setting-up the build environment.

Change-Id: Iab203cb299f0547c8683fc6d6394b23d25ea0b32
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>
2 files changed