add lxml to dependency list

Signed-off-by: antmicro <antmicro@debian>

setup.py

diff --git a/setup.py b/setup.py
index d5d3bef..14b64ef 100644
--- a/setup.py
+++ b/setup.py
@@ -14,7 +14,7 @@
     long_description_content_type="text/markdown",
     url="https://github.com/SymbiFlow/python-symbiflow-v2x",
     packages=setuptools.find_packages(),
-    install_requires=['ply', 'pyjson'],
+    install_requires=['lxml', 'pyjson'],
     setup_requires=["pytest-runner"],
     tests_require=["pytest"],
     classifiers=[