fix(c-api) Call wasi_env_delete manually.

`wasi_get_imports` isn't taking ownership of `wasi_env_t` (despites
what is written in the documentation). And it must not take ownership
of it, since one could use it with the `wasi_env_read_stdout` &
sibling functions after having called `wasi_get_imports`.

Consequently, this patch calls `wasi_env_delete` to avoid leaking
memory.

lib/cli/src/commands/wasmer_create_exe_main.c

@@ -143,6 +143,7 @@ int main(int argc, char* argv[]) {
   
   #ifdef WASI
   bool get_imports_result = wasi_get_imports(store, module, wasi_env, &imports);
+  wasi_env_delete(wasi_env);
 
   if (!get_imports_result) {
     fprintf(stderr, "Error getting WASI imports!\n");