fix: remove package from AndroidManifest.xml (#2600)

# Summary

Fixes #2599 

Starting with `v15.8.0`, we support `react-native@0.73+`, which
eliminates the need to worry about AGP versions below 7. Consequently,
the `package` attribute in `AndroidManifest.xml` can be safely removed,
along with the corresponding check in `build.gradle`.

## Test Plan

Build the app on all supported versions

## Compatibility

| OS      | Implemented |
| ------- | :---------: |
| Android |    ✅      |

android/build.gradle

@@ -81,10 +81,8 @@ def FRESCO_VERSION = getFrescoVersion()
 
 android {
     compileSdkVersion safeExtGet('compileSdkVersion', 28)
-    def agpVersion = com.android.Version.ANDROID_GRADLE_PLUGIN_VERSION
-    if (agpVersion.tokenize('.')[0].toInteger() >= 7) {
     namespace "com.horcrux.svg"
-    }
+    def agpVersion = com.android.Version.ANDROID_GRADLE_PLUGIN_VERSION
     if (agpVersion.tokenize('.')[0].toInteger() >= 8) {
         buildFeatures {
             buildConfig = true

android/src/main/AndroidManifest.xml

@@ -1,2 +1 @@
-<manifest package="com.horcrux.svg">
-</manifest>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"/>