Update tester_linux.yml

Author: DilumAluthge

.buildkite/pipelines/main/platforms/tester_linux.yml

@@ -63,9 +63,9 @@ steps:
       if [[   "${GROUP?}" == "all" ]]; then
         export TESTS="all"
       elif [[ "${GROUP?}" == "net" ]]; then
-        export TESTS="Downloads LibGit2 LibGit2/online"
+        export TESTS="Downloads LibGit2 LibGit2/online download"
       elif [[ "${GROUP?}" == "no-net" ]]; then
-        export TESTS="all --skip Downloads"
+        export TESTS="all --skip Downloads LibGit2/online download"
       else
         echo "Invalid value for GROUP: ${GROUP?}"
         exit 1