Upgrade Swagger

[withinfocus]

Type of change

- [ ] Bug fix
- [ ] New feature development
- [X] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
- [X] Build/deploy pipeline (DevOps)
- [ ] Other

Objective

Upgrades Swagger manually, including the global tool.

Code changes

• src/Api/Api.csproj: Library upgrade
• src/Identity/Identity.csproj: Library upgrade
• .config/dotnet-tools.json: Library upgrade and formatting
• .github/workflows/build.yml: Explicitly install .NET 6 SDK

Before you submit

• Please check for formatting errors (dotnet format --verify-no-changes) (required)
• If making database changes - make sure you also update Entity Framework queries and/or migrations
• Please add unit tests where it makes sense to do so (encouraged but not required)
• If this change requires a documentation update - notify the documentation team
• If this change has particular deployment requirements - notify the DevOps team