Upgrade bazel to 4.2.2

The latest `rules_go` release requires at least 4.2.0. We're at 4.1.0
currently.

https://blog.bazel.build/2021/08/18/bazel-4.2.html
https://github.com/bazelbuild/bazel/releases/tag/4.2.1
https://github.com/bazelbuild/bazel/releases/tag/4.2.2

Steps to produce the file:

    $ wget 'https://github.com/bazelbuild/bazel/releases/download/4.2.2/bazel-4.2.2-linux-x86_64'
    $ xz bazel-4.2.2-linux-x86_64
    $ mv bazel-4.2.2-linux-x86_64.xz bazel_4.2.2.xz

Change-Id: Ia98af20057e38a9b98911f500eacba5f37db66a1
Signed-off-by: Philipp Schrader <philipp.schrader@gmail.com>
diff --git a/tools/bazel b/tools/bazel
index ef6372b..e72b44e 100755
--- a/tools/bazel
+++ b/tools/bazel
@@ -24,7 +24,7 @@
   exec "${BAZEL_OVERRIDE}" "$@"
 fi
 
-readonly VERSION="4.1.0"
+readonly VERSION="4.2.2"
 
 readonly DOWNLOAD_DIR="${HOME}/.cache/bazel"
 # Directory to unpack bazel into.  This must change whenever bazel changes.