Minor release Bolt 3.1.0

Notable changes:

• Fix: Allow taxonomies in contentlinks again. #5698
• Fix: Case-insensitive username lookup at login. #5696
• Fix: Change slug to singular_slug in Edit Record screen. #5688
• Fix: Exclude 'bower_components', 'node_modules' in .gitignore. #5689
• Fix: Fix for uploading to themes/ folder in backend. #5679
• Fix: Fix slash in taxonomies #5675
• Fix: Handle Upload exceptions better #5683
• Fix: Improve Hydration Process in Repeaters #5670, #5684
• Fix: More session save_path bugfixes. #5691
• Fix: Show correct error message on incorrect login attempt. #5697