Adjust perf test to exit gracefully if perf not available

Author: mp15

tests/test_core_perf.py

@@ -1,10 +1,17 @@
 import time
 
-import codecarbon.core.perf
+import codecarbon.core.cpu
+
+try:
+    from codecarbon.core.perf import Perf
+except ImportError:
+    Perf = None
 
 
 def test_perf():
-    x = codecarbon.core.perf.Perf(["energy-pkg"])
+    if codecarbon.core.cpu.is_perf_available() == False:
+        return
+    x = Perf(["energy-pkg"])
     x.start()
     time.sleep(20)
     x.delta(20.0)