build(deps): bump alpine in /taskcluster/docker/linux (#2233)

Bumps alpine from `beefdbd` to `1e42bbe`.

---
updated-dependencies:
- dependency-name: alpine
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

taskcluster/docker/linux/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:latest@sha256:beefdbd8a1da6d2915566fde36db9db0b524eb737fc57cd1367effd16dc0d06d
+FROM alpine:latest@sha256:1e42bbe2508154c9126d48c2b8a75420c3544343bf86fd041fb7527e017a4b4a
 LABEL maintainer="Mozilla Release Engineering <release+docker@mozilla.com>"
 
 # Add worker user