fix(harness): add custom wasm-pack to build script (#940)

crates/harness/build.wasm.sh

@@ -3,6 +3,9 @@
 # Ensure the script runs in the folder that contains this script
 cd "$(dirname "$0")"
 
+# A specific version of `wasm-pack` must be installed to build the WASM binary
+cargo install --git https://github.com/rustwasm/wasm-pack.git --rev 32e52ca
+
 rustup run nightly \
     wasm-pack build executor \
         --profile wasm \