Update Dockerfile with missing packages

Signed-off-by: Archana <archana.madhavan@silabs.com>
Signed-off-by: Asfandyar Orakzai <asfandyar.orakzai@silabs.com>
diff --git a/tests/docker/bionic/Dockerfile b/tests/docker/bionic/Dockerfile
index 8fa5814..4b5739c 100644
--- a/tests/docker/bionic/Dockerfile
+++ b/tests/docker/bionic/Dockerfile
@@ -60,6 +60,11 @@
     pkg-config \
     && rm -rf /var/lib/apt/lists/*
 
+# The following packages are required for validating Python files.
+# The version of Pylint is set to 2.4.4 to match CI.
+RUN python3 -m pip install \
+    packaging mypy pylint==2.4.4
+
 # Jinja2 and jsonschema is required for driver dispatch code generation.
 RUN python3 -m pip install \
     jinja2==2.10.1 types-jinja2 \