Drops com.android.tools:desugar_jdk_libs

Suspecting that it's the cause of a frequent CI failure building `samples:dungeon:common:compileKotlin`:

```
Caused by: org.gradle.api.GradleException: Could not read directory path '/Users/runner/work/workflow-kotlin/workflow-kotlin/samples/dungeon/common/build/kotlin/compileKotlin/caches-jvm/inputs'.
```

At any rate, it's the only interesting thing about that build, and doesn't appear to be necessary any longer.

Author: rjrjr

buildSrc/src/main/java/Dependencies.kt

@@ -52,7 +52,6 @@ object Dependencies {
   const val cycler = "com.squareup.cycler:cycler:0.1.9"
 
   // Required for Dungeon Crawler sample.
-  const val desugar_jdk_libs = "com.android.tools:desugar_jdk_libs:1.1.5"
   const val leakcanary = "com.squareup.leakcanary:leakcanary-android:2.8.1"
   const val radiography = "com.squareup.radiography:radiography:2.4.0"
   const val rxandroid2 = "io.reactivex.rxjava2:rxandroid:2.1.1"

samples/dungeon/app/build.gradle.kts

@@ -13,17 +13,9 @@ android {
 
     testInstrumentationRunner = "com.squareup.sample.dungeon.DungeonTestRunner"
   }
-
-  compileOptions {
-    // Required for SnakeYAML.
-    isCoreLibraryDesugaringEnabled = true
-  }
 }
 
 dependencies {
-  // Required for SnakeYAML.
-  "coreLibraryDesugaring"(Dependencies.desugar_jdk_libs)
-
   debugImplementation(Dependencies.leakcanary)
 
   implementation(project(":samples:dungeon:common"))