v3.9.1

What's Changed

• Update releases.md by @zslade in #1273
• Readme formatting by @RobinL in #1274
• Use tmp_path in deterministic link test by @ADBond in #1275
• allow lowercase postcodes by @RossKen in #1263
• update linting bash script by @ThomasHepworth in #1290
• clean datediff code by @ThomasHepworth in #1291
• save_settings_to_json -> save_model_to_json by @RossKen in #1283
• Add PR template by @RossKen in #1253
• Settings Topic Guide by @RossKen in #1292
• Comparison pseudo symlinks by @ThomasHepworth in #1279
• Update parameter_estimate_comparisons.json by @samnlindsay in #1301

Full Changelog: v3.9.0...v3.9.1