package/sdl2_ttf: bump version to 2.0.18

Update the license hash because of a change in copyright year:
-  Copyright (C) 1997-2019 Sam Lantinga <slouken@libsdl.org>
+  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>

Signed-off-by: Peter Thompson <peter.macleod.thompson@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/sdl2_ttf/sdl2_ttf.hash

@@ -1,3 +1,3 @@
 # Locally calculated
-sha256  a9eceb1ad88c1f1545cd7bd28e7cbc0b2c14191d40238f531a15b01b1b22cd33  SDL2_ttf-2.0.15.tar.gz
-sha256  f6370809c9f644760920d9945c5be07aed17664975f2e4741013d4d9a2ec696f  COPYING.txt
+sha256  7234eb8883514e019e7747c703e4a774575b18d435c22a4a29d068cb768a2251  SDL2_ttf-2.0.18.tar.gz
+sha256  e211dfe7e2c36e64048be886fe3f2bbba8732ce4dd77b596a355d3abbec775a4  COPYING.txt

package/sdl2_ttf/sdl2_ttf.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-SDL2_TTF_VERSION = 2.0.15
+SDL2_TTF_VERSION = 2.0.18
 SDL2_TTF_SOURCE = SDL2_ttf-$(SDL2_TTF_VERSION).tar.gz
 SDL2_TTF_SITE = http://www.libsdl.org/projects/SDL_ttf/release
 SDL2_TTF_LICENSE = Zlib