Nicer version parsing

Author: microbit-robert

src/Makefile

@@ -147,7 +147,7 @@ $(BUILD)/micropython.js: $(OBJ) jshal.js simulator-js
 
 simulator-js:
 	npx esbuild '--define:process.env.STAGE="$(STAGE)"' ./simulator.ts --bundle --outfile=$(BUILD)/simulator.js --loader:.svg=text
-	npx esbuild --define:process.env.VERSION="$$(cat ../package.json | grep '"version":' | sed 's/"version": //' | sed 's/,//' | sed 's/ //g')" ./sw.ts --bundle --outfile=$(BUILD)/sw.js
+	npx esbuild --define:process.env.VERSION="$$(node -e 'process.stdout.write(`"` + require("../package.json").version + `"`)')" ./sw.ts --bundle --outfile=$(BUILD)/sw.js
 
 include $(TOP)/py/mkrules.mk