Bump mozrunner version for web-platform tests.

Differential Revision: https://phabricator.services.mozilla.com/D49781

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1587463
gecko-commit: 37a84a2d91ff1ccc04d00149e59a83f2f6ed1c66
gecko-integration-branch: autoland
gecko-reviewers: jgraham
diff --git a/tools/wptrunner/requirements_firefox.txt b/tools/wptrunner/requirements_firefox.txt
index 2021f55..45442de 100644
--- a/tools/wptrunner/requirements_firefox.txt
+++ b/tools/wptrunner/requirements_firefox.txt
@@ -6,6 +6,6 @@
 moznetwork==0.27
 mozprocess==1.0.0
 mozprofile==2.3.0
-mozrunner==7.5.1
+mozrunner==7.6.0
 mozversion==2.1.0
 psutil==5.6.3