workflows: add cc for cross compile

Signed-off-by: Morten Linderud <morten@linderud.pw>

Author: Foxboron

.github/workflows/build.yml

@@ -14,8 +14,8 @@ jobs:
       matrix:
         include:
           - {GOOS: linux, GOARCH: amd64}
-          - {GOOS: linux, GOARCH: arm, GOARM: 6}
-          - {GOOS: linux, GOARCH: arm64}
+          - {GOOS: linux, GOARCH: arm, GOARM: 6, CC=aarch64-linux-gnu-gcc}
+          - {GOOS: linux, GOARCH: arm64, CC=aarch64-linux-gnu-gcc}
     steps:
       - name: Install Go
         uses: actions/setup-go@v2