fix DNT for firefox

Dockerfile

 FROM node:alpine
 RUN apk add --no-cache git && \
-    git clone https://github.com/mikecao/umami.git /umami && \
-    cd umami && \
+    git clone https://github.com/mikecao/umami.git /umami
+WORKDIR /umami
+ADD src/fix.diff /umami/fix.diff
+RUN git apply fix.diff && \
     npm install
 ADD src/docker-entrypoint.sh /
 WORKDIR /umami

src/fix.diff

+diff --git a/lib/web.js b/lib/web.js
+index 4b70389..c5c9fca 100644
+--- a/lib/web.js
++++ b/lib/web.js
+@@ -49,7 +49,7 @@ export const hook = (_this, method, callback) => {
+ 
+ export const doNotTrack = () => {
+   if (window.doNotTrack || navigator.doNotTrack || navigator.msDoNotTrack || 'msTrackingProtectionEnabled' in window.external) {
+-    if (window.doNotTrack == "1" || navigator.doNotTrack == "yes" || navigator.doNotTrack == "1" || navigator.msDoNotTrack == "1" || window.external.msTrackingProtectionEnabled()) {
++    if (window.doNotTrack == "1" || navigator.doNotTrack == "yes" || navigator.doNotTrack == "1" || navigator.msDoNotTrack == "1" || (window.external.msTrackingProtectionEnabled && window.external.msTrackingProtectionEnabled())) {
+       return true
+     } else {
+       return false