docs/dart: Update unstable version example

OPNA2608 8dff0785 dc279167

Changed files
+1 -1
doc
languages-frameworks
+1 -1
doc/languages-frameworks/dart.section.md
···
flutter.buildFlutterApplication {
pname = "firmware-updater";
-
version = "unstable-2023-04-30";
+
version = "0-unstable-2023-04-30";
# To build for the Web, use the targetFlutterPlatform argument.
# targetFlutterPlatform = "web";