refactor(DivisionTest): use non plural form

src/test/java/edu/ntnu/idatt1002/k1g4/CupTest.java

+package edu.ntnu.idatt1002.k1g4;
+
+public class CupTest {
+
+}

src/test/java/edu/ntnu/idatt1002/k1g4/DivisionsTest.java → src/test/java/edu/ntnu/idatt1002/k1g4/DivisionTest.java

 package edu.ntnu.idatt1002.k1g4;
 
-public class DivisionsTest {
+public class DivisionTest {
 
 
 }
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