Remove forcing arch to arm64 for libpng

Diffs=
5c03e1640 Remove forcing arch to arm64 for libpng (#4715)
diff --git a/.rive_head b/.rive_head
index 016e81c..b2df691 100644
--- a/.rive_head
+++ b/.rive_head
@@ -1 +1 @@
-404a04d352143cd24760ada60546771eb1a9bd7e
+5c03e164093d308c72626d079201479a8a325256
diff --git a/dependencies/premake5_libpng.lua b/dependencies/premake5_libpng.lua
index 2844fd9..9b567c3 100644
--- a/dependencies/premake5_libpng.lua
+++ b/dependencies/premake5_libpng.lua
@@ -36,7 +36,6 @@
         libpng .. '/pngwutil.c'
     }
 
-    architecture('ARM64')
     do
         files {
             libpng .. '/arm/arm_init.c',