Add HTTP QUERY method

[i-am-the-slime]

Summary

• add the QUERY constructor standardized by RFC 9842
• render it as QUERY and recognize it case-insensitively in fromString
• add focused coverage for rendering, parsing, and the existing custom-method fallback
• replace the removed prepare-0.15 package-set branch with the working immutable psc-0.15.0-20220502 tag
• restore CI by updating deprecated GitHub Actions, pinning the Dhall-compatible PureScript/Spago toolchain, and removing compiler flags unsupported by PureScript 0.15 from the legacy Pulp check

Verification

• npx --yes spago@0.20.9 test
• GitHub Actions build passed, including strict Spago compilation, formatting, and Bower/Pulp compatibility