gradle: Bump required flags version

- Bump buildToolsVersion, compileSdkVersion, and targetSdkVersion to 29 (We are currently shipping on Android 10)
- Bump minSdkVersion to 25 (We are only backwards compatiable till Android 7.1)
Signed-off-by: Aayush Gupta <theimpulson@e.email>

app/build.gradle

@@ -6,13 +6,13 @@ plugins {
 }
 
 android {
-    compileSdkVersion 28
-    buildToolsVersion '28.0.3'
+    compileSdkVersion 29
+    buildToolsVersion '29.0.2'
 
     defaultConfig {
         applicationId "foundation.e.apps"
-        minSdkVersion 21
-        targetSdkVersion 27
+        minSdkVersion 25
+        targetSdkVersion 29
         versionCode 10
         versionName "1.1.6"