ci: Enable GLES 3.1 testing on db820c (a530).

The driver exposes GLES3.1, so let's make sure we're not regressing its
featureset.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4685>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 0824670..9d79b31 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -848,6 +848,12 @@
     CI_NODE_INDEX: 1
     CI_NODE_TOTAL: 100
 
+arm64_a530_gles31:
+  extends:
+    - arm64_a530_gles3
+  variables:
+    DEQP_VER: gles31
+
 # RADV CI
 .test-radv:
   extends: .radv-rules