Update Bundler to avoid permission error on GHA

[pocke]

The following error happens in GHA and updating Bundler will solve it.

The installation path is insecure. Bundler cannot continue.

ref: ruby/rubygems#7983 (comment)

Also, this update causes the following error on Windows ucrt and mswin CI.

Bundler found mismatched checksums. This is a potential security risk.
net-smtp (0.5.0)
sha256=5fc0415e6ea1cc0b3dfea7270438ec22b278ca8d524986a3ae4e5ae8d087b42a
    from the API at https://rubygems.org/
net-smtp (0.5.0)
sha256=5040e34a1bbf11aa501e53d036d9c5e17a30004a08ed24304d7b1dc69c806c4d
    from the gem at D:/ruby-ucrt/lib/ruby/gems/3.5.0+0/cache/net-smtp-0.5.0.gem

If you trust the API at https://rubygems.org/, to resolve this issue you can:
1. remove the gem at
D:/ruby-ucrt/lib/ruby/gems/3.5.0+0/cache/net-smtp-0.5.0.gem
  2. run `bundle install`

To ignore checksum security warnings, disable checksum validation with
  `bundle config set --local disable_checksum_validation true`

Because their Rubies are the latest build. So, the bundled gems contain different content from the RubyGems' one.
To solve this problem, I updated the GHA to remove all bundled gems before bundle install on these CI.

[pocke]

Writing PowerShell is difficult for me🙃 I use Ruby instead...

[soutaro]

👍