Do not use attrs 21.1.0

csmarchbanks · csmarchbanks · commit 269bbdedaaea · 2021-05-28T10:54:02.000-06:00
Attrs 21.1.0 does not work with Python 3.4. The release has been yanked
from pypi, but will still get used sometimes, so specify not to install
21.1.0.

Signed-off-by: Chris Marchbanks &lt;csmarchbanks@gmail.com&gt;
diff --git a/tox.ini b/tox.ini
@@ -6,6 +6,8 @@ envlist = coverage-clean,py2.7,py3.4,py3.5,py3.6,py3.7,py3.8,py3.9,pypy2.7,pypy3
 deps =
     coverage
     pytest
+; Python 3.4 fails if using 21.1.0.
+    attrs!=21.1.0
 
 [testenv:py2.7]
 deps =
