python-utils: drop support for versions older than python3.6

We make all but python2_7 fatal as the latter still has some holdouts.

BUG=b:187794810
TEST=CQ passes

Change-Id: I49af65f946892a76921d13e55718f55cd96d1ab4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/eclass-overlay/+/4191984
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
diff --git a/eclass/python-utils-r1.eclass b/eclass/python-utils-r1.eclass
index 8a8ea8b..b8a5661 100644
--- a/eclass/python-utils-r1.eclass
+++ b/eclass/python-utils-r1.eclass
@@ -77,10 +77,10 @@
 	# keep in sync with _PYTHON_ALL_IMPLS!
 	# (not using that list because inline patterns shall be faster)
 	case "${impl}" in
-		python2_7|python3_[6789]|pypy3)
+		python3_[6-9]|pypy3)
 			return 0
 			;;
-		jython2_7|pypy|pypy1_[89]|pypy2_0|python2_[56]|python3_[12345])
+		python2_7)
 			return 1
 			;;
 		*)