✨ Add flutter support

CHANGELOG.MD

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [v1.2.0] - 2021-07-12
+### Added
+- Add flutter dependencies
+
 ## [v1.1.0] - 2021-07-12
 ### Added
 - Add labels

Dockerfile

@@ -96,4 +96,23 @@ RUN git clone https://github.com/danger/kotlin.git _danger-kotlin && \
 # setup environment variables
 ENV PATH=$PATH:/usr/local/kotlinc/bin
 
+# flutter
+ENV FLUTTER_CHANNEL="stable"
+ENV FLUTTER_VERSION="2.2.1"
+ENV FLUTTER_URL="https://storage.googleapis.com/flutter_infra/releases/$FLUTTER_CHANNEL/linux/flutter_linux_$FLUTTER_VERSION-$FLUTTER_CHANNEL.tar.xz"
+ENV FLUTTER_HOME="/opt/flutter"
+
+RUN curl -o flutter.tar.xz $FLUTTER_URL \
+  && mkdir -p $FLUTTER_HOME \
+  && tar xf flutter.tar.xz -C /opt \
+  && rm flutter.tar.xz
+
+ENV PATH=$PATH:$FLUTTER_HOME/bin
+
+RUN flutter config --no-analytics \
+  && flutter precache \
+  && yes "y" | flutter doctor --android-licenses \
+  && flutter doctor \
+  && flutter update-packages
+
 VOLUME /root/.gradle

README.MD

@@ -8,4 +8,5 @@ Contains:
 - Latest 8 Android version SDKs + Platform CLI tools
 - gcloud CLI tool
 - danger-kotlin 
+- Flutter 2.2.3 binaries