Only check libraries against MSRV (from #1558)

.github/workflows/rust.yml

@@ -36,16 +36,12 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        rust: [stable, beta, "1.63.0"]
+        rust: [stable, beta]
         exclude:
           - os: macos-latest
             rust: beta
-          - os: macos-latest
-            rust: "1.63.0"
           - os: windows-latest
             rust: beta
-          - os: windows-latest
-            rust: "1.63.0"
 
     runs-on: ${{ matrix.os }}
 
@@ -70,6 +66,21 @@ jobs:
           command: test
           args: --manifest-path fuzz/Cargo.toml
 
+  msrv:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: "1.63.0"
+          override: true
+      - uses: Swatinem/rust-cache@v1
+      - uses: actions-rs/cargo@v1
+        with:
+          command: check
+          args: --lib --all-features -p quinn-udp -p quinn-proto -p quinn
+
   lint:
     runs-on: ubuntu-latest
     steps: