CI: Fix twister invocation

The `west twister` command seems to be broken right now.  Fix this by
directly invoking the twister script better.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

.github/workflows/build.yml

@@ -77,6 +77,6 @@ jobs:
           lscpu
           df -h
 
-          west twister -M all -T samples -T tests -v --inline-logs --integration -j 4 \
+          ../zephyr/scripts/twister -M all -T samples -T tests -v --inline-logs --integration -j 4 \
              --timeout-multiplier 2 \
              $(cat etc/platforms.txt)