testing/xmrig-proxy: upgrade to 6.12.0

Ref https://github.com/xmrig/xmrig-proxy/releases/tag/v6.12.0
7 jobs for !20655 with xmrig-proxy in 1 minute and 32 seconds (queued for 3 seconds)
detached
Status Job ID Name Coverage
  Lint
passed #375812
docker-alpine x86_64
lint

00:00:19

 
  Build
failed #375817
docker-alpine ci-build aarch64
build-aarch64

00:00:08

failed #375818
docker-alpine ci-build armv7
build-armv7

00:00:11

passed #375816
docker-alpine ci-build ppc64le
build-ppc64le

00:00:42

passed #375815
docker-alpine ci-build s390x
build-s390x

00:01:00

passed #375814
docker-alpine ci-build x86
build-x86

00:00:18

failed #375813
docker-alpine ci-build x86_64
build-x86_64

00:00:05

 
Name Stage Failure
failed
build-x86_64 Build
No job log
failed
build-aarch64 Build
No job log
failed
build-armv7 Build
No job log