Fix matplotlib ver (#156)

* Fixed matplotlib version

* Change matplotlib version based on arch

* Don't install matplotlib on ppc

Pip package of matplotlib is broken on ppc.

* Update setup.py

setup.py

@@ -17,6 +17,7 @@
 # limitations under the License.
 # *****************************************************************
 """
+import platform
 from setuptools import find_packages, setup
 import open_ce
 
@@ -31,9 +32,14 @@ def get_readme():
     "jinja2",
     "networkx",
     "junit-xml",
-    "matplotlib==3.5.0",
 ]
 
+# We are installing matplotlib only on x86. It is needed for one of the pytests (get_graph_test.py)
+# which is run in the PR check and it runs on x86. On ppc, matplotlib's pip package isn't working.
+
+if platform.machine() == 'x86_64':
+  REQUIRED_PACKAGES.append("matplotlib==3.5.0")
+
 setup(
     name="open-ce-builder",
     version=open_ce.__version__,