Added script for auto incrementing build number

.gitignore

@@ -1,5 +1,3 @@
-increment_build_number.sh
-
 # Do not remove or rename entries in this file, only add new ones
 # See https://github.com/flutter/flutter/issues/128635 for more context.
 

increment_build_number.sh

@@ -0,0 +1,2 @@
+build_number=$(awk -F'+' '/version:/ {print $2}' pubspec.yaml); build_number=${build_number:-0};
+sed -i '' -E "s/(version: [0-9]+\.[0-9]+\.[0-9]\+)[0-9]*/\1$((build_number + 1))/" pubspec.yaml