Update changelog for upcoming 0.20.3

[nkrkv]

Bug fixes

• [build] Fix macOS distro download filename. Now it has proper .dmg extension. (Proper file names for uploaded GCloud files containing spaces #1198)
• [core] Fix opening projects saved prior to 0.20.0 with some pins explicitly bound to Never. Notably, the bug led to a transpilation error when using digital-output from own xod/core fork. (Fix bound value migration for pulses #1207)
• [core] Fix untitled outputs name assignment for C++. Previously, all untitled outputs got name output_OUT. Now they are output_OUT1, output_OUT2, and so on. (Fix bug in the transpilation: wrong output pin labels #1204)
• [core] Fix C++ generation from generic nodes containing not-implemented-in-xod which previously was silently failing. (Dont forget autogenerated patches when extracting bound inputs #1225)
• [ide] Minimize performance regression in 0.20.x caused by generics resolution (Tweak performance of type deduction #1213, Optimize memoized selector comparators #1214)
• [ide] Fix occasional [Object object] errors when deploying. Now they are still there but formatted properly. (Fix [Object object] in deploy pane messages #1203)
• [ide] Format transpilation errors that previously appeared as cryptic objects. (Fix error reporting #1230)
• [ide] Fix uncaught error handling. Now they pop up as a regular error for easier reporting. (Fix error reporting #1230)
• [ide] Fix canceling when opening a project. Previously it broke the current project (Fix canceling of open project in browser ide causes exception #1202)