Update cpp-httplib to v0.28.0

packages/c/cpp-httplib/xmake.lua

@@ -7,6 +7,7 @@ package("cpp-httplib")
     set_urls("https://github.com/yhirose/cpp-httplib/archive/refs/tags/$(version).tar.gz",
              "https://github.com/yhirose/cpp-httplib.git")
 
+    add_versions("v0.28.0", "ccb32f9832c906d571f61794f453223dbb724ba738265551e3cd28ca325b529d")
     add_versions("v0.26.0", "a66f908f50ccb119769adce44fe1eac75f81b6ffab7c4ac0211bb663ffeb2688")
     add_versions("v0.23.1", "410a1347ed6bcbcc4a19af8ed8ad3873fe9fa97731d52db845c4c78f3f9c31e6")
     add_versions("v0.22.0", "fcfea48c8f2c386e7085ef8545c8a4875efa30fa6d5cf9dd31f03c6ad038da9d")