Azure/GitLab/Travis: Add SPL unit tests

Run SPL unit tests in all test environments.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/.azure-pipelines.yml b/.azure-pipelines.yml
index 473ddee..a78c8d6 100644
--- a/.azure-pipelines.yml
+++ b/.azure-pipelines.yml
@@ -182,7 +182,7 @@
           OVERRIDE: "-O clang-10"
         sandbox_spl:
           TEST_PY_BD: "sandbox_spl"
-          TEST_PY_TEST_SPEC: "test_ofplatdata or test_handoff"
+          TEST_PY_TEST_SPEC: "test_ofplatdata or test_handoff or test_spl"
         sandbox_flattree:
           TEST_PY_BD: "sandbox_flattree"
         evb_ast2500: