workflows: add unidiff for compliance workflow

Required due to Zephyr upstream changes.

Signed-off-by: Andreas Moltumyr <[email protected]>

Author: anhmolt

.github/workflows/compliance.yml

@@ -30,6 +30,7 @@ jobs:
         pip3 install -U yamllint
         pip3 install lxml==4.9.1
         pip3 install  -U python-magic junitparser==2.8.0 gitlint pylint pykwalify
+        pip3 install -U unidiff
         pip3 install --user -U west
         pip3 show -f west