Fix Konflux build platform arch

The GOOS and GOARCH env vars need to be set explicitly, otherwise we
just build the linux x86 binary over and over. Looks like this
regression was introduced in commit b8db99c.

I think restoring the export on those two vars would also have
worked.

Ref: https://issues.redhat.com/browse/SECURESIGN-1054

Author: simonbaird

build.sh

@@ -35,7 +35,7 @@ for os_arch in ${BUILDS}; do
     [[ "$GOOS" == "windows" ]] && DOT_EXE=".exe" || DOT_EXE=""
     BINFILE="ec_${GOOS}_${GOARCH}${DOT_EXE}"
     echo "Building ${BINFILE} for ${EC_FULL_VERSION}"
-    go build \
+    GOOS="${GOOS}" GOARCH="${GOARCH}" go build \
         -trimpath \
         --mod=readonly \
         -ldflags="-s -w -X github.com/enterprise-contract/ec-cli/internal/version.Version=${EC_FULL_VERSION}" \