Fix missing line break in proguard-unity.

[timbotimbo]

Description

The build script adds -keep class com.unity3d.plugin.* { *; } to the proguard file.
In most setups this simply works, but in some configurations it gets appended to a line that doesn't end in a line break.

For example in #762
-dontwarn com.google.android.play.core.tasks.Task-keep class com.unity3d.plugin.* { *; }

I combined both lines that edit the proguard file to ensure it always add a \n.

-  proguardText = proguardText.Replace("-ignorewarnings", "-keep class com.xraph.plugin.** { *; }\n-ignorewarnings");
-  proguardText += "-keep class com.unity3d.plugin.* { *; }";
+  proguardText = proguardText.Replace("-ignorewarnings", "-keep class com.xraph.plugin.** { *; }\n-keep class com.unity3d.plugin.* { *; }\n-ignorewarnings");

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

[RoyalCoder88]

This problem was fixed by @timbotimbo, it's a very common problem for a lot of users!