build(emsdk): update to latest version and fix unused import warning

Updates CI/CD emsdk from pinned 3.1.43 to latest (4.0.22), resolving a version
mismatch between local dev (which used latest) and production builds. This
discrepancy likely caused production-only ErrnoError bugs that were impossible
to reproduce locally.

pacman/src/main.rs

@@ -3,6 +3,7 @@
 #![cfg_attr(coverage_nightly, feature(coverage_attribute))]
 #![cfg_attr(coverage_nightly, coverage(off))]
 
+#[cfg(not(target_os = "emscripten"))]
 use std::env;
 
 use crate::{app::App, constants::LOOP_TIME};