Use "bundle exec" in gemspec CI job

[synthead]

Fixes #333!

This PR uses bundle exec with ruby -e 'require "timex_datalink_client"' in the gemspec CI job. This ensures that the expected gem versions are loaded when this CI job runs 👍

From #333:

The gemspec CI job is defined as:

timex_datalink_client/.github/workflows/ci.yml

Lines 33 to 42 in 263bffa

	gemspec:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v3
	- uses: ruby/setup-ruby@v1
	with:
	bundler-cache: true
	- run: gem build timex_datalink_client.gemspec
	- run: gem install timex_datalink_client-*.gem
	- run: ruby -e 'require "timex_datalink_client"'

The last "run" step does not use bundle exec, so the gem requirements in Gemfile.lock are not honored. Currently, this causes failures in CI like this one:

• https://github.com/synthead/timex_datalink_client/actions/runs/13321858323/job/37207940688

Run ruby -e 'require "timex_datalink_client"'
/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/activesupport-7.0.8.7/lib/active_support/logger_thread_safe_level.rb:12:in `<module:LoggerThreadSafeLevel>': uninitialized constant ActiveSupport::LoggerThreadSafeLevel::Logger (NameError)

    Logger::Severity.constants.each do |severity|
          ^^^^^^^^^^
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/activesupport-7.0.8.7/lib/active_support/logger_thread_safe_level.rb:9:in `<module:ActiveSupport>'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/activesupport-7.0.8.7/lib/active_support/logger_thread_safe_level.rb:8:in `<top (required)>'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/activesupport-7.0.8.7/lib/active_support/logger_silence.rb:5:in `<top (required)>'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/activesupport-7.0.8.7/lib/active_support/logger.rb:3:in `<top (required)>'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/activesupport-7.0.8.7/lib/active_support.rb:29:in `<top (required)>'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/activemodel-7.0.8.7/lib/active_model.rb:26:in `<top (required)>'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/timex_datalink_client-0.12.3/lib/timex_datalink_client/protocol_1/alarm.rb:3:in `<top (required)>'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from /opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/gems/3.2.0/gems/timex_datalink_client-0.12.3/lib/timex_datalink_client.rb:6:in `<top (required)>'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:159:in `require'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:159:in `rescue in require'
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:39:in `require'
	from -e:1:in `<main>'
<internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require': cannot load such file -- timex_datalink_client (LoadError)
	from <internal:/opt/hostedtoolcache/Ruby/3.2.2/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from -e:1:in `<main>'
Error: Process completed with exit code 1.

This 👆 is due to the gem being required without the gem versions set via bundle exec 👍