[prerender] contentHash: md5 => md4.

Webpack uses md4 for all hashes by default (see [1] and [2])

[1] webpack/webpack#6549
[2] webpack/loader-utils#114

package.json

@@ -48,6 +48,7 @@
     "html-webpack-plugin": "^3.2.0",
     "is-empty": "^1.2.0",
     "jquery": "^3.4.1",
+    "js-md4": "^0.3.2",
     "jsontoxml": "^1.0.1",
     "lodash": "^4.17.15",
     "lodash-es": "^4.17.15",
@@ -71,7 +72,6 @@
     "sass-loader": "^8.0.2",
     "scrivito": "^1.11.0",
     "slick-carousel": "^1.6.0",
-    "spark-md5": "^3.0.1",
     "terser-webpack-plugin": "^2.3.5",
     "typescript": "^3.8.3",
     "webpack": "^4.42.1",

src/prerenderContent/contentHash.js

@@ -1,6 +1,6 @@
-import { hash as md5 } from "spark-md5";
+import md4 from "js-md4";
 
-/** Generates a 20 long hex value, based the md5 of the given string */
+/** Generates a 20 long hex value, based the md4 of the given string */
 export default async function contentHash(input) {
-  return md5(input).substr(0, 20);
+  return md4(input).substr(0, 20);
 }