Remove @fastify/accepts dependency

[Pezmc]

Description

The accepts header parsing was previously only used in one place, which actually bypassed most of the parsing.

Now checking for application/openmetrics-text more naively and saving FlowForge one NPM dependency.

Related Issue(s)

N/a

Checklist

• I have read the contribution guidelines
• [-] Suitable unit/system level tests have been added and they pass
• [-] Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on flowforge/helm to update ConfigMap Template
  • Issue/PR raised on flowforge/CloudProject to update values for Staging/Production

Labels

• Backport needed? -> add the backport label
• Includes a DB migration? -> add the area:migration label

[knolleary]

Resolved the merge conflict - okay to merge once tests pass

[Pezmc]

The merge conflict resolution has re-introduced accept, fixing it now. Good test of our linting though, it caught accepts wasn't included in our package.json.

[knolleary]

🤦🏻 whilst figuring out what the conflict was I made a mental note to make sure I didn't reintroduce the dependency then got distracted at the vital moment. My apols.