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 5 slowest examples (1.17 seconds, 100% of total time)

Example	Description	Time in seconds
spec/unit/recipes/server_spec.rb:62	openvpn::server When push_options & push_routes are set, on Ubuntu creates a world readable CRL file	1.1662
spec/unit/recipes/server_spec.rb:25	openvpn::server When push_options & push_routes are set, on Ubuntu makes a server.conf from template with dhcp options	0.00298
spec/unit/recipes/server_spec.rb:32	openvpn::server When push_options & push_routes are set, on Ubuntu makes a server.conf from template with multiple push routes	0.00235
spec/unit/recipes/server_spec.rb:21	openvpn::server When push_options & push_routes are set, on Ubuntu converges successfully	0.0005
spec/unit/recipes/server_spec.rb:39	openvpn::server When push_options & push_routes are set, on Ubuntu executes gencrl with correction parameters	0.00045