Rely on pytest-perf 0.16 for nanosecond precision in performance tests.

Closes #539

Author: jaraco

exercises.py

@@ -51,7 +51,4 @@ def normalize_perf():
     # python/cpython#143658
     import importlib_metadata  # end warmup
 
-    # operation completes in < 1ms, so repeat it to get visibility
-    # https://github.com/jaraco/pytest-perf/issues/12
-    for _ in range(1000):
-        importlib_metadata.Prepared.normalize('sample')
+    importlib_metadata.Prepared.normalize('sample')

pyproject.toml

@@ -38,7 +38,7 @@ test = [
 	# local
 	"packaging",
 	"pyfakefs",
-	"pytest-perf >= 0.9.2",
+	"pytest-perf >= 0.16",
 ]
 
 doc = [