only run coverage on master ci

.github/workflows/ci.yml

@@ -20,7 +20,6 @@ jobs:
         version:
           - 1.52.0 # MSRV for -server and -tls
           - stable
-          - nightly
 
     name: ${{ matrix.target.name }} / ${{ matrix.version }}
     runs-on: ${{ matrix.target.os }}
@@ -88,7 +87,7 @@ jobs:
         if: matrix.target.triple == 'x86_64-pc-windows-gnu'
         uses: actions-rs/cargo@v1
         with: { command: ci-check-min }
-      
+
       - name: check full
         # TODO: compile OpenSSL and run tests on MinGW
         if: >
@@ -118,7 +117,7 @@ jobs:
         run: |
           cargo install cargo-cache --version 0.6.2 --no-default-features --features ci-autoclean
           cargo-cache
-  
+
   build_and_test_lower_msrv:
     name: Linux / 1.46 (lower MSRV)
     runs-on: ubuntu-latest
@@ -146,35 +145,6 @@ jobs:
         run: |
           cargo install cargo-cache --version 0.6.2 --no-default-features --features ci-autoclean
           cargo-cache
-  
-  coverage:
-    name: coverage
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-
-      - name: Install Rust (nightly)
-        uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable-x86_64-unknown-linux-gnu
-          profile: minimal
-          override: true
-
-      - name: Generate Cargo.lock
-        uses: actions-rs/cargo@v1
-        with: { command: generate-lockfile }
-      - name: Cache Dependencies
-        uses: Swatinem/rust-cache@v1.3.0
-    
-      - name: Generate coverage file
-        if: github.ref == 'refs/heads/master'
-        run: |
-          cargo install cargo-tarpaulin
-          cargo tarpaulin --out Xml --verbose
-      - name: Upload to Codecov
-        if: github.ref == 'refs/heads/master'
-        uses: codecov/codecov-action@v1
-        with: { file: cobertura.xml }
 
   rustdoc:
     name: rustdoc