increase version number

- 0.3.18 supports the new memory allocator of the nightly compiler
3 jobs for v0.3.18 in 37 seconds
latest
Status Job ID Name Coverage
  Prepare
passed #719768
linux shell
docker

00:00:03

 
  Build
failed #719769
docker
build

00:00:34

 
  Test
skipped #719770
docker
test:cargo
 
Name Stage Failure
failed
build Build
               found fn pointer `unsafe fn(&mut mm::allocator::Heap, core::alloc::Layout) -> core::result::Result<_, _>`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0053`.
error: could not compile `rusty-hermit`.

To learn more, run the command again with --verbose.
ERROR: Job failed: exit code 1