Drop 99% coverage threshold flag for 3.10 in noxfile (#593)

noxfile.py

@@ -19,7 +19,6 @@
 import os
 import platform
 import shutil
-import sys
 
 import nox
 
@@ -68,16 +67,9 @@ def cover(session):
     if ON_WINDOWS_CI:
         return
 
-    # 3.10 produces different coverage results for some reason
-    # see https://github.com/theacodes/nox/issues/478
-    fail_under = 100
-    py_version = sys.version_info
-    if py_version.major == 3 and py_version.minor == 10:
-        fail_under = 99
-
     session.install("coverage[toml]")
     session.run("coverage", "combine")
-    session.run("coverage", "report", f"--fail-under={fail_under}", "--show-missing")
+    session.run("coverage", "report", "--fail-under=100", "--show-missing")
     session.run("coverage", "erase")