fix unit tests

Author: gmuth

src/test/kotlin/de/gmuth/ipp/core/IppAttributeTests.kt

@@ -113,7 +113,7 @@ class IppAttributeTests {
 
     @Test
     fun attributeToString() {
-        assertEquals("foo (1setOf integer) = 1,2,3", IppAttribute("foo", Integer, 1, 2, 3).toString())
+        assertEquals("foo (1setOf integer) = 1, 2, 3", IppAttribute("foo", Integer, 1, 2, 3).toString())
     }
 
     @Test

src/test/kotlin/de/gmuth/ipp/core/IppCollectionTests.kt

@@ -17,7 +17,7 @@ class IppCollectionTests {
 
     @Test
     fun toStringValue() {
-        assertEquals("{foo=a,b}", collection.toString())
+        assertEquals("{foo=a, b}", collection.toString())
     }
 
     @Test