gnu: python-umap-learn: Disable failing test.

* gnu/packages/machine-learning.scm (python-umap-learn)[arguments]: Disable
one failing test.

Change-Id: Ic8f5f60f7d7bea0c24b417932daab3d54813d5fd

gnu/packages/machine-learning.scm

@@ -3928,6 +3928,10 @@ methodxs at scale on CPU or GPU.")
     (build-system pyproject-build-system)
     (arguments
      (list
+      #:test-flags
+      ;; XXX: this one fails with unusually large deviation from the expected
+      ;; result.
+      '(list "-k" "not test_umap_update_large")
       #:phases
       #~(modify-phases %standard-phases
           ;; Numba needs a writable dir to cache functions.