testing/cargo-c: upgrade to 0.6.18

Ref https://github.com/lu-zero/cargo-c/releases/tag/v0.6.18
7 jobs for !14904 with cargo-c in 8 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Lint
failed #253534
docker-alpine x86_64 allowed to fail
lint

00:00:08

 
  Build
canceled #253539
docker-alpine ci-build aarch64
build-aarch64

canceled #253540
docker-alpine ci-build armv7
build-armv7

canceled #253538
docker-alpine ci-build ppc64le
build-ppc64le

canceled #253537
docker-alpine ci-build s390x
build-s390x

canceled #253536
docker-alpine ci-build x86
build-x86

canceled #253535
docker-alpine ci-build x86_64
build-x86_64

 
Name Stage Failure
failed
lint Lint
No job log