package/sdl2_net: fix license hash after 2.2.0 bump

Fixes:
http://autobuild.buildroot.net/results/37e5075a5c790d5c96bdc72c44d4362a16ae00bb/

Commit b41ff7dd46 (package/sdl2_net: bump version to 2.2.0) forgot to
update the license hash / filename, breaking the build.

Upstream renamed COPYING.txt to LICENSE.txt, changed white space and updated
the copyright years, so update the hash to match:

diff -uw sdl2_net-2.0.1/COPYING.txt sdl2_net-2.2.0/LICENSE.txt
--- sdl2_net-2.0.1/COPYING.txt  2016-01-03 08:57:09.000000000 +0100
+++ sdl2_net-2.2.0/LICENSE.txt  2022-08-17 18:55:22.000000000 +0200
@@ -1,6 +1,4 @@
-/*
-  SDL_net:  An example cross-platform network library for use with SDL
-  Copyright (C) 1997-2016 Sam Lantinga <slouken@libsdl.org>
+Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>

   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
@@ -17,4 +15,4 @@
   2. Altered source versions must be plainly marked as such, and must not be
      misrepresented as being the original software.
   3. This notice may not be removed or altered from any source distribution.
-*/
+

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/sdl2_net/sdl2_net.hash

@@ -1,3 +1,3 @@
 # Locally calculated
 sha256  4e4a891988316271974ff4e9585ed1ef729a123d22c08bd473129179dc857feb  SDL2_net-2.2.0.tar.gz
-sha256  f09845a238245402a8b8388db6634d8a5b2c3e1dc098f16f9d8c74a276ef4594  COPYING.txt
+sha256  fcb07e07ac6bc8b2fcf047b50431ef4ebe5b619d7ca7c82212018309a9067426  LICENSE.txt

package/sdl2_net/sdl2_net.mk

@@ -8,7 +8,7 @@ SDL2_NET_VERSION = 2.2.0
 SDL2_NET_SOURCE = SDL2_net-$(SDL2_NET_VERSION).tar.gz
 SDL2_NET_SITE = http://www.libsdl.org/projects/SDL_net/release
 SDL2_NET_LICENSE = Zlib
-SDL2_NET_LICENSE_FILES = COPYING.txt
+SDL2_NET_LICENSE_FILES = LICENSE.txt
 SDL2_NET_INSTALL_STAGING = YES
 SDL2_NET_DEPENDENCIES = sdl2 host-pkgconf