Update tox.ini (#75)

Author: MikeWooster

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    requests{216,217,218,219,220,221,222,223,224,225}-tenacity{51,60,61,62,63,70,80}
+    requests{216,217,218,219,220,221,222,223,224,225,226}-tenacity{51,60,61,62,63,70,80}
     lint
 
 [testenv]
@@ -15,6 +15,7 @@ deps =
     requests223: requests>=2.23,<2.24
     requests224: requests>=2.24,<2.25
     requests225: requests>=2.25,<2.26
+    requests226: requests>=2.26,<2.27
     tenacity51: tenacity>=5.1.0,<5.2.0
     tenacity60: tenacity>=6.0.0,<6.1.0
     tenacity61: tenacity>=6.1.0,<6.2.0