message: fix: extensionHook not being used
  fixes
diff: @@ -126,14 +126,13 @@ export class RedocNormalizedOptions {
  allowedMdComponents: Dict<MDXComponentMeta>;
  constructor(raw: RedocRawOptions, defaults: RedocRawOptions = {}) {
  - let hook;
  raw = { ...defaults, ...raw };
  - if (raw.theme && raw.theme.extensionsHook) {
  - hook = raw.theme.extensionsHook;
  - raw.theme.extensionsHook = undefined;
  - }
  - this.theme = resolveTheme(mergeObjects({} as any, defaultTheme, raw.theme || {}));
  - this.theme.extensionsHook = hook;
  + const hook = raw.theme && raw.theme.extensionsHook;
  + this.theme = resolveTheme(
  + mergeObjects({} as any, defaultTheme, { ...raw.theme, extensionsHook: undefined }),
  + );
  +
  + this.theme.extensionsHook = hook as any;
  this.scrollYOffset = RedocNormalizedOptions.normalizeScrollYOffset(raw.scrollYOffset);
  this.hideHostname = RedocNormalizedOptions.normalizeHideHostname(raw.hideHostname);
  