use raw identifier syntax for mod 'async' as it is a keyword since 2018 edition

6 jobs for master in 3 minutes and 50 seconds (queued for 2 seconds)
latest
Status Name Job ID Coverage
  Build
passed build:linux #33708

00:01:18

passed build:linux:stable #33707

00:01:34

passed build:redox #33709

00:01:17

 
  Test
passed test:linux #33711

00:01:39

passed test:linux:stable #33710

00:01:53

failed test:redox #33712

00:02:15

 
Name Stage Failure
failed
test:redox Test
  0000000000000000: GUARD PAGE
kernel:INFO -- SIGNAL 11, CPU 1, PID ContextId(37)
kernel:INFO -- NAME file:/root/target/x86_64-unknown-redox/debug/deps/termion-c2fe7db58afec023
redoxerd: signal: 11

## redoxer (failure) ##
error: test failed, to rerun pass '--lib'
redoxer cargo: exit status: 1
Cleaning up file based variables
ERROR: Job failed: exit code 1