test: bump test-run to version w/ updated luatest

Bump test-run to new version with the following improvements:

- Bump luatest to 0.5.7-25-g9e117e6 [1]

[1] tarantool/test-run@7c77fcb

NO_DOC=testing stuff
NO_TEST=testing stuff
NO_CHANGELOG=testing stuff

test-run @ 7c77fcb6

-Subproject commit 8baea548c186a14ef92a3da778aa8d66a80b251e
+Subproject commit 7c77fcb67d6ae034dc2784194813dd54b5bfaad2