Remove target section from CI

matrix.include does not require the target section to be present because it
specifies the specific matrix combinations to be run.

.github/workflows/ci.yml

@@ -40,10 +40,11 @@ jobs:
   build:
     strategy:
       matrix:
-        target: [ x86_64-unknown-linux-gnu, x86_64-apple-darwin, x86_64-pc-windows-msvc, armv7-unknown-linux-gnueabihf ]
         include:
           - target: x86_64-unknown-linux-gnu
             os: ubuntu-latest
+          - target: armv7-unknown-linux-gnueabihf
+            os: ubuntu-latest
           - target: x86_64-apple-darwin
             os: macos-latest
           - target: x86_64-pc-windows-msvc
@@ -85,7 +86,6 @@ jobs:
       RUST_TEST_TASKS: 2
     strategy:
       matrix:
-        target: [ x86_64-unknown-linux-gnu, x86_64-apple-darwin, armv7-unknown-linux-gnueabihf ]
         include:
           - target: x86_64-unknown-linux-gnu
             os: ubuntu-latest
@@ -99,12 +99,6 @@ jobs:
 
       - uses: Swatinem/rust-cache@v1.2.0
 
-      - name: Install compiler for armhf arch
-        if: matrix.target == 'armv7-unknown-linux-gnueabihf'
-        run: |
-          sudo apt-get update
-          sudo apt-get install gcc-arm-linux-gnueabihf
-
       - name: Build tests
         env:
           CARGO_TARGET_ARMV7_UNKNOWN_LINUX_GNUEABIHF_LINKER: arm-linux-gnueabihf-gcc