installPackage function
Implementation
void installPackage(File pubspec, String package, String version,
{bool devDep = false}) {
String tempPubSpec = pubspec.readAsStringSync();
if (devDep) {
tempPubSpec = tempPubSpec.replaceFirst(
"dev_dependencies:\n", "dev_dependencies:\n $package: ^$version\n");
} else {
tempPubSpec = tempPubSpec.replaceFirst(
"dependencies:\n", "dependencies:\n $package: ^$version\n");
}
pubspec.writeAsStringSync(tempPubSpec);
printSuccess("Установлен $package версии $version");
}