SAI: replace dead play store link with fdroid link

README.md

@@ -178,7 +178,7 @@ Pull requests are welcome. See [Contributing](CONTRIBUTING.md) for hints.
 * [IzzyOnDroid](https://gitlab.com/sunilpaulmathew/izzyondroid) - An unofficial client for IzzyOnDroid F-Droid Repository `GPL-3.0`
 * [Obtainium](https://github.com/ImranR98/Obtainium) - Get Android App Updates Directly From the Source `GPL-3.0`
 * [PI](https://github.com/SanmerApps/PI) - Package installer that allows overwriting the package requester and executor `MIT`
-* [SAI](https://play.google.com/store/apps/details?id=com.aefyr.sai) - Android split APKs installer `GPL-3.0` [(Source code)](https://github.com/Aefyr/SAI)
+* [SAI](https://f-droid.org/de/packages/com.aefyr.sai.fdroid/) - Android split APKs installer `GPL-3.0` [(Source code)](https://github.com/Aefyr/SAI)
 * [skydroid](https://github.com/redsolver/skydroid) - A decentralized domain-based App Store for Android `GPL-3.0`
 
 ### Miscellaneous