gnu: mtr: Remove dependency on libcap.

This is only needed so that mtr can call setcap(8) from its Makefile,
which we don't want it to do.

See https://codeberg.org/guix/guix/issues/8614

* gnu/packages/networking.scm (mtr)[inputs]: Remove libcap.

Change-Id: I0c532cc4772ed2336bf3251aa5dc4b857b47fe7e

gnu/packages/networking.scm

@@ -3687,7 +3687,7 @@ can be whipped up with little effort.")
     (build-system gnu-build-system)
     (native-inputs (list pkg-config))
     (inputs
-     (list jansson libcap ncurses))
+     (list jansson ncurses))
     (arguments
      `(#:tests? #f))                    ; tests require network access
     (home-page "https://www.bitwizard.nl/mtr/")