Drop `py2` tag from the wheel name (#320)

* Drop `py2` tag from the wheel name

* Add a change note for PR #320
diff --git a/releasenotes/notes/pr320-py3-only-wheel-tag.yaml b/releasenotes/notes/pr320-py3-only-wheel-tag.yaml
new file mode 100644
index 0000000..e85f85f
--- /dev/null
+++ b/releasenotes/notes/pr320-py3-only-wheel-tag.yaml
@@ -0,0 +1,5 @@
+---
+other: >-
+  Corrected the PyPI-published wheel tag to match the
+  metadata saying that the release is Python 3 only.
+...
diff --git a/setup.cfg b/setup.cfg
index 8491b6a..3e4fbee 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -37,9 +37,6 @@
     sphinx
     tornado>=4.5
 
-[wheel]
-universal = 1
-
 [tool:pytest]
 filterwarnings =
     # Show any DeprecationWarnings once