teeworlds: replace python with python3 in hostmakedepends

Build instructions in readme.md mention python 3 as a build dependency
in section "Building on Linux or macOS (CMake)", subsection "Installing
dependencies".

Related to void-linux#38229.

srcpkgs/teeworlds/template

@@ -2,7 +2,7 @@
 pkgname=teeworlds
 version=0.7.5
 revision=2
-hostmakedepends="bam python pkg-config"
+hostmakedepends="bam python3 pkg-config"
 makedepends="zlib-devel SDL2-devel glu-devel freetype-devel"
 short_desc="Retro multiplayer shooter"
 maintainer="Leah Neukirchen <[email protected]>"