Install Bundler gem helper tasks

[tvdeyen]

Very useful for building and releasing gems

Checklist

• I have structured the commits for clarity and conciseness.
• I have added relevant automated tests for this change.

[mergify]

It looks like this PR is missing a label to determine the type of change it introduces. The maintainer should add one of the following labels:

• bug for bugfixes.
• enhancement for new features and improvements.
• documentation for documentation changes.
• security for security patches.
• removed for feature removals.
• infrastructure for internal changes that should not go in the changelog.

Additionally, the maintainer may also want to add one of the following:

• breaking for breaking changes.
• deprecated for feature deprecations.

Once the correct labels have been set, simply remove the needs changelog label label from this PR so I can merge it.

[tvdeyen]

Just saw that we already use the gem-release gem. Why? Bundler has gem support build right in.

But anyhow the release tasks are not included in the extensions take tasks. That should be fixed either way.

[tvdeyen]

gem-release has much more features that are very helpful. Closing