Pin ethereum/tests subrepository to a newer version

cburgdorf · cburgdorf · commit 97657bde2903 · 2018-08-14T15:42:18.000+02:00
Related to #1152
diff --git a/fixtures b/fixtures
@@ -1 +1 @@
-Subproject commit 47b09f42c0681548a00da5ab1c98808b368af49a
+Subproject commit 2bb0c3da3bbb15c528bcef2a7e5ac4bd73f81f87
