net: update submodule to latest commits

And fix module definition pointing to `dev` branch by default.

Signed-off-by: Piotr Bocheński <piotr@bochen.ski>

Author: b0ch3nski

.gitmodules

@@ -35,7 +35,6 @@
 [submodule "src/net"]
 	path = src/net
 	url = https://github.com/tinygo-org/net.git
-	branch = dev
 [submodule "lib/wasi-cli"]
 	path = lib/wasi-cli
 	url = https://github.com/WebAssembly/wasi-cli