chore: Use Parity 2.7.2 (#588)

* bump

* remove comment
4 jobs for v0.4.3-beta in 9 minutes and 20 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #378786
linux-docker
linux-test

00:01:57

 
  Build
passed #378787
linux-docker
linux-build

00:07:22

passed #378788
darwin-shell
osx-build

00:06:46

passed #378789
linux-docker
win-build

00:06:23