Set PYTHONPATH so gdb loads our venv

Change-Id: I87eb58f45f348403e9330c3ab8f3374b9954b780

kgdb.sh

diff --git a/kgdb.sh b/kgdb.sh
index 2e4f187..1f457d0 100755
--- a/kgdb.sh
+++ b/kgdb.sh
@@ -35,6 +35,7 @@
 USE_SEL4_EXTENSIONS="true"
 USE_SEL4_SYMBOL_AUTOSWITCHING="false"
 
+export PYTHONPATH=${ROOTDIR}/cache/python-venv/lib/python3.11/site-packages/:${PYTHONPATH}
 export SOURCE_DIR=${ROOTDIR}/cantrip
 export BUILD_DIR=$CANTRIP_OUT