Bump Mastodon API to 2.7.2

Current advertised Mastodon API version: 2.5.0

From mastodon release notes, may have missed some, may have got non-applicable ones or one we do not want to add, some might already be resolved:

2.7.2

• (!979 (merged)) Add registrations attribute to GET /api/v1/instance https://github.com/tootsuite/mastodon/pull/10060
• (!981 (merged)) Add vapid_key to POST /api/v1/apps and GET /api/v1/apps/verify_credentials https://github.com/tootsuite/mastodon/pull/10058

2.7.0

• Add joining several hashtags in a single column https://github.com/tootsuite/mastodon/pull/8904
• (!1005 (closed)) Add REST API for creating an account https://github.com/tootsuite/mastodon/pull/9572
• Add exclude_reblogs option to account statuses API https://github.com/tootsuite/mastodon/pull/9640
• (!989 (merged)) Add scheduled statuses https://github.com/tootsuite/mastodon/pull/9706
• Allow unauthenticated REST API access to GET /api/v1/accounts/:id/statuses https://github.com/tootsuite/mastodon/pull/9573
• (!978 (merged)) Change API error message for unconfirmed accounts https://github.com/tootsuite/mastodon/pull/9625

2.6.5

• Change lists to display replies to others on the list and list owner https://github.com/tootsuite/mastodon/pull/9324

2.6.2

• Fix filter ID not being a string in REST API https://github.com/tootsuite/mastodon/pull/9303

2.6.0

• (!947 (closed) !1041 (closed)) Conversations API https://github.com/tootsuite/mastodon/pull/8832 / Revamped direct messages column https://github.com/tootsuite/mastodon/pull/9022
• (!976 (merged)) Support backwards pagination https://github.com/tootsuite/mastodon/pull/8736 #351 (closed)
• (!999 (merged)) Support different accounts on OAuth authorize page https://github.com/tootsuite/mastodon/pull/8655
• Add card attribute to statuses returned from REST API https://github.com/tootsuite/mastodon/pull/9120

I’m assigning this issue to me but feel free to ask to add some of them or help verify the presence of some in pleroma, I’ll start on 2.6.0 and end on 2.7.2.