Release Betty 0.4.0b1

[bartfeenstra]

Blocked by

• Remove wait_to_thread() #2057
• Expose repositories for all plugin types on Project #2118
• Ensure Project.new() and Project.new_temporary() have a similar signature #2126
• Ensure errors and cancellations result in graceful exits #2123
• The generate API still contains legacy favicon code #2137
• Make Configurable require Configuration #2146
• Use PluginInstanceConfiguration throughout all configuration  #2149
• Consider removing ExtensionConfiguration #2152
• PluginInstanceConfiguration must not depend on plugin repositories #2162
• Rename project's copyright configuration key to copyright_notice #2166
• Update pip dependencies #2169
• Upgrade npm dependencies #2170
• Rename PluginRepository.map() to mapping() #2171
• Rename GeneratedEntityId to InternalEntityId #2174
• Make ConfigurationCollection.load_item() private #2181