gnu: maven-resolver-provider: Fix build.

* gnu/packages/maven (maven-resolver-provider)[arguments]:
Add the'add-sisu-shebang phase after unpack.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/maven.scm

@@ -1509,6 +1509,10 @@ (define-public maven-resolver-provider
        #:tests? #f; dependency loop on maven-core (@Component RepositorySystem)
        #:phases
        (modify-phases %standard-phases
+         (add-after 'unpack 'add-sisu-shebang
+           (lambda _
+             (substitute* "sisu.sh"
+               (("^## T") "#!/bin/sh\n## T"))))
          (add-before 'build 'generate-sisu-named
            (lambda _
              (mkdir-p "build/classes/META-INF/sisu")