Adds rustfmt to CI

.github/workflows/rustfmt.yml

@@ -0,0 +1,24 @@
+name: rustfmt
+on: [push, pull_request]
+jobs:
+
+  rustfmt:
+    name: Format
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Install nightly toolchain with rustfmt available
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+          components: rustfmt
+
+      - name: Run cargo fmt
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check

src/stream.rs

@@ -273,7 +273,7 @@ where
 {
     Utf8(Utf8LossyDecoder<Sink, A>),
     #[cfg(feature = "encoding")]
-    Encoding(Box<encoding::RawDecoder>, Sink),
+    Encoding(Box<dyn encoding::RawDecoder>, Sink),
     #[cfg(feature = "encoding_rs")]
     EncodingRs(encoding_rs::Decoder, Sink),
 }