Update HeadlessPrometheusExporter 1.2.2

[jae1911]

• The mod id matches the harmony id if used by the mod and starts with the same id as your author folder
• All used links are valid
• Your ResoniteMod.Version must match the version being added in the manifest and follow Semantic Versioning
• Your AssemblyVersion should match the mod version
• You have included an accurate sha256 hash for each artifact
• Do not remove old mods. Instead, use the deprecated flag
• Follow the Resonite Policies and Guidelines and Mod Submission Guidelines

Update 1.2.2 building against .NET 9 + security fix in System.Text.Json.

https://g.j4.lc/general-stuff/resonite/headless-prometheus-exporter/-/releases/1.2.2