add potential duplicates workflow

+ declare window variable with let as per https://github.com/notion-enhancer/notion-enhancer/issues/298#issuecomment-737749264

.github/workflows/potential-duplicates.yml

@@ -0,0 +1,26 @@
+name: potential duplicates
+on:
+  issues:
+    types: [opened, edited]
+jobs:
+  run:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: bubkoo/potential-duplicates@v1
+        with:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          # Label to set, when potential duplicates are detected.
+          label: potential-duplicate
+          # Get issues with state to compare. Supported state: 'all', 'closed', 'open'.
+          state: all
+          # If similarity is higher than this threshold([0,1]), issue will be marked as duplicate.
+          threshold: 0.6
+          # Reactions to be add to comment when potential duplicates are detected.
+          # Available reactions: "-1", "+1", "confused", "laugh", "heart", "hooray", "rocket", "eyes"
+          reactions: 'confused'
+          # Comment to post when potential duplicates are detected.
+          comment: >
+            potential duplicates:  
+            {{#issues}}
+              - [#{{ number }}] {{ title }} ({{ accuracy }}%)
+            {{/issues}}

mods/core/createWindow.js

@@ -40,7 +40,7 @@ module.exports = (store, __exports) => {
       rect.width = focused_window.getSize()[0];
       rect.height = focused_window.getSize()[1];
     }
-    const window = new electron.BrowserWindow({
+    let window = new electron.BrowserWindow({
       show: false,
       backgroundColor: '#ffffff',
       titleBarStyle: 'hiddenInset',