chore(deps): update actions/checkout action to v6

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	v5 → v6

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Release Notes

actions/checkout (actions/checkout)

v6

Compare Source

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Slowest examples

Top 10 slowest examples (0.63 seconds, 77.76% of total time)

Example	Description	Time in seconds
spec/distro_install_spec.rb:14	install_varnish::distro_install does not configure the varnish vendor repo	0.11373
spec/distro_install_spec.rb:29	install_varnish::distro_install creates the default varnish config and VCLs	0.0948
spec/vendor_install_spec.rb:29	install_varnish::vendor_install creates the default varnish config and VCLs	0.06762
spec/vendor_install_spec.rb:22	install_varnish::vendor_install enables the varnish service, enables and configures the varnishlog service	0.05348
spec/distro_install_spec.rb:18	install_varnish::distro_install installs varnish	0.05205
spec/vendor_install_spec.rb:18	install_varnish::vendor_install installs varnish	0.05119
spec/vendor_install_spec.rb:39	install_varnish::vendor_install creates the log & ncsa template, enables the varnishlog and varnishncsa service	0.05009
spec/distro_install_spec.rb:39	install_varnish::distro_install creates the log & ncsa template, enables the varnishlog and varnishncsa service	0.04999
spec/distro_install_spec.rb:22	install_varnish::distro_install enables the varnish service, enables and configures the varnishlog service	0.04961
spec/vendor_install_spec.rb:34	install_varnish::vendor_install sets up varnishncsa logging	0.04929