ci: use Ruby with latest rubygems version

The CI was failing with the following error when running with Ruby 3.0
against `devise` 3.0.

```
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

current directory:
/home/runner/work/devise-webauthn/devise-webauthn/vendor/bundle/ruby/3.0.0/gems/sqlite3-2.0.4/ext/sqlite3
/opt/hostedtoolcache/Ruby/3.0.7/x64/bin/ruby -I
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0 -r
./siteconf20260303-2303-pvjn4q.rb extconf.rb
Building sqlite3-ruby using packaged sqlite3.
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

	from extconf.rb:51:in `configure_packaged_libraries'
	from extconf.rb:17:in `configure'
	from extconf.rb:284:in `<main>'

extconf failed, exit code 1

Gem files will remain installed in
/home/runner/work/devise-webauthn/devise-webauthn/vendor/bundle/ruby/3.0.0/gems/sqlite3-2.0.4
for inspection.
Results logged to
/home/runner/work/devise-webauthn/devise-webauthn/vendor/bundle/ruby/3.0.0/extensions/x86_64-linux/3.0.0/sqlite3-2.0.4/gem_make.out

/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/rubygems/ext/builder.rb:93:in
`run'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/rubygems/ext/ext_conf_builder.rb:47:in
`block in build'
  /opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/tempfile.rb:317:in `open'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/rubygems/ext/ext_conf_builder.rb:26:in
`build'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/rubygems/ext/builder.rb:159:in
`build_extension'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/rubygems/ext/builder.rb:193:in
`block in build_extensions'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/rubygems/ext/builder.rb:190:in
`each'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/rubygems/ext/builder.rb:190:in
`build_extensions'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/rubygems/installer.rb:837:in
`build_extensions'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/rubygems_gem_installer.rb:71:in
`build_extensions'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/rubygems_gem_installer.rb:28:in
`install'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/source/rubygems.rb:204:in
`install'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/installer/gem_installer.rb:54:in
`install'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/installer/gem_installer.rb:16:in
`install_from_spec'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/installer/parallel_installer.rb:186:in
`do_install'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/installer/parallel_installer.rb:177:in
`block in worker_pool'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/worker.rb:62:in
`apply_func'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/worker.rb:57:in
`block in process_queue'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/worker.rb:54:in
`loop'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/worker.rb:54:in
`process_queue'
/opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/bundler/worker.rb:91:in
`block (2 levels) in create_threads'

An error occurred while installing sqlite3 (2.0.4), and Bundler cannot continue.

In devise_5_0.gemfile:
  sqlite3
```

This is an known issue for Rubies 2.6 up to 3.1 when used with rubygems
older than v3.4.9: ruby/rubygems#6611.

This commits uses `setup-ruby`'s `rubygems` params so that the latest
available `rubygems` version is used for our rubies.

References:
- ruby/rubygems#6611
- https://github.com/ruby/setup-ruby/blob/896e71e063dc0933bb442a54e949d75291991ecb/action.yml#L11-L17

Author: santiagorodriguez96

.github/workflows/ruby.yml

@@ -79,6 +79,7 @@ jobs:
       uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}
+        rubygems: latest
         bundler-cache: true
 
     - name: Run tests