Add `explicit_cache_control`, bump versions, rm deprecations

[amotpan]

what

• Add explicit_cache_control to pagerule.tf (thanks to @amotplan)
• Bump versions and remove deprecations (thanks to @toketas)

why

• Whether origin Cache-Control action is "on" or "off".

references

• https://registry.terraform.io/providers/cloudflare/cloudflare/latest/docs/resources/page_rule#explicit_cache_control
• https://registry.terraform.io/providers/cloudflare/cloudflare/latest/docs/resources/healthcheck
• Closes https://github.com/cloudposse/terraform-cloudflare-zone/pull/7
• Closes https://github.com/cloudposse/terraform-cloudflare-zone/pull/11
• Related to https://github.com/cloudposse/terraform-cloudflare-zone/pull/8
• Related to https://github.com/cloudposse/terraform-cloudflare-zone/pull/9
• Related to https://github.com/cloudposse/terraform-cloudflare-zone/pull/10

[nitrocode]

/test all

[nitrocode]

/test terratest

[nitrocode]

/test test/readme

[nitrocode]

/test test/bats