Update swift-syntax link to swiftlang/swift-syntax (#57)

Author: ahoppen

docker/Dockerfile

@@ -18,7 +18,7 @@ RUN echo 'export PATH="$HOME/.tools:$PATH"' >> $HOME/.profile
 
 # swift-format
 ARG swiftformat_version=509.0.0
-RUN git clone --branch $swiftformat_version --depth 1 https://github.com/apple/swift-format $HOME/.tools/swift-format-source
+RUN git clone --branch $swiftformat_version --depth 1 https://github.com/swiftlang/swift-format $HOME/.tools/swift-format-source
 RUN cd $HOME/.tools/swift-format-source && swift build -c release
 RUN ln -s $HOME/.tools/swift-format-source/.build/release/swift-format $HOME/.tools/swift-format