README: Revise download links

Author: davidfstr

README.md

@@ -17,9 +17,9 @@ Additional documentation will be available once Crystal is no longer **in beta**
 Download ⬇︎
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-* [macOS 10.14 and later](https://github.com/davidfstr/Crystal-Web-Archiver/releases/download/v1.3.0b/crystal-mac-1.3.0b.dmg)
+* [macOS 10.14 and later](https://github.com/davidfstr/Crystal-Web-Archiver/releases/download/v1.4.0b/crystal-mac-1.4.0b.dmg)
     * You will need to [right-click or Control-click on the application and select "Open" to open it for the first time](https://github.com/davidfstr/Crystal-Web-Archiver/issues/20).
-* [Windows 7, 8, 10](https://github.com/davidfstr/Crystal-Web-Archiver/releases/download/v1.3.0b/crystal-win-1.3.0b.exe)
+* [Windows 7, 8, 10](https://github.com/davidfstr/Crystal-Web-Archiver/releases/download/v1.4.0b/crystal-win-1.4.0b.exe)
 
 
 Tutorial ⭐