report hypothesis stats in run

since hypothesis executes good few hundred test cases, do
report that they have been run when the user runs the test suite
specified in readme...

tox.ini

@@ -20,7 +20,7 @@ commands = coverage run --branch -m pytest {posargs:src/ecdsa}
 
 [testenv:coverage]
 sitepackages=True
-commands = coverage run --branch -m pytest {posargs:src/ecdsa}
+commands = coverage run --branch -m pytest --hypothesis-show-statistics {posargs:src/ecdsa}
 
 [testenv:speed]
 commands = {envpython} speed.py