Upgrade to setuptools 61.1.0

This fixes Python 3.10 compat, but does remove Python2 compat.

Test: treehugger
Change-Id: I8e19ad8dec6b34482bfbe996413d3f793ada276c
diff --git a/exercises.py b/exercises.py
new file mode 100644
index 0000000..76176be
--- /dev/null
+++ b/exercises.py
@@ -0,0 +1,6 @@
+def measure_startup_perf():
+    # run by pytest_perf
+    import subprocess
+    import sys  # end warmup
+
+    subprocess.check_call([sys.executable, '-c', 'pass'])