gnu: php: Build against Oniguruma 6.

* gnu/packages/php.scm (php)[inputs]: Change ONIGURUMA-5 to ONIGURUMA.
* gnu/packages/textutils.scm (oniguruma-5): Remove variable.

gnu/packages/php.scm

@@ -364,7 +364,7 @@
        ("libxpm" ,libxpm)
        ("libxslt" ,libxslt)
        ("libx11" ,libx11)
-       ("oniguruma" ,oniguruma-5)
+       ("oniguruma" ,oniguruma)
        ("openldap" ,openldap)
        ("openssl" ,openssl)
        ("pcre" ,pcre2)

gnu/packages/textutils.scm

@@ -492,20 +492,6 @@ characteristic of this library is that different character encoding for every
 regular expression object can be specified.")
     (license license:bsd-2)))
 
-;; PHP < 7.3.0 requires this old version.  Remove once no longer needed.
-(define-public oniguruma-5
-  (package
-    (inherit oniguruma)
-    (version "5.9.6")
-    (source (origin
-              (method url-fetch)
-              (uri (string-append "https://github.com/kkos/"
-                                  "oniguruma/releases/download/v" version
-                                  "/onig-" version ".tar.gz"))
-              (sha256
-               (base32
-                "19s79vsclqn170mw0ajwv7j37qsbn4f1yjz3yavnhvva6c820r6m"))))))
-
 (define-public antiword
   (package
     (name "antiword")