Remove an excessive test

Author: dkhalanskyjb

core/commonTest/src/kotlinx/serialization/BasicTypesSerializationTest.kt

@@ -194,27 +194,6 @@ class BasicTypesSerializationTest {
         assertEquals(Duration.parseIsoString(durationString), other)
     }
 
-    @OptIn(ExperimentalTime::class)
-    @Test
-    fun testEncodeInstant() {
-        val sb = StringBuilder()
-        val out = KeyValueOutput(sb)
-
-        val instant = Instant.parse("2020-12-09T09:16:56.000124Z")
-        out.encodeSerializableValue(Instant.serializer(), instant)
-
-        assertEquals("\"${instant}\"", sb.toString())
-    }
-
-    @OptIn(ExperimentalTime::class)
-    @Test
-    fun testDecodeInstant() {
-        val instantString = "2020-12-09T09:16:56.000124Z"
-        val inp = KeyValueInput(Parser(StringReader("\"$instantString\"")))
-        val other = inp.decodeSerializableValue(Instant.serializer())
-        assertEquals(Instant.parse(instantString), other)
-    }
-
     @Test
     fun testNothingSerialization() {
         // impossible to deserialize Nothing