gnu: r-seurat: Fix build.

This is a follow-up to commit e4d4046999

* gnu/packages/cran.scm (r-seurat)[arguments]: Patch NAMESPACE file.

gnu/packages/cran.scm

@@ -26491,6 +26491,18 @@ (define-public r-seurat
                 "1mp3py00bmzj4541d8ry5sfzkpfzvnl9dpa8n4qhakd13dl30xdn"))))
     (properties `((upstream-name . "Seurat")))
     (build-system r-build-system)
+    ;; This is needed because r-spatstat has been split up and there has
+    ;; been no new release of Seurat since then.
+    (arguments
+     `(#:phases
+       (modify-phases %standard-phases
+         (add-after 'unpack 'fix-spatstat-import
+           (lambda _
+             (substitute* "NAMESPACE"
+               (("importFrom\\(spatstat,markvario\\)")
+                "importFrom(spatstat.core,markvario)")
+               (("importFrom\\(spatstat,ppp\\)")
+                "importFrom(spatstat.geom,ppp)")))))))
     (propagated-inputs
      `(("r-cluster" ,r-cluster)
        ("r-cowplot" ,r-cowplot)