some fixes

Author: Cadabra

src/DateRecurrenceR/Core/DayOfMonth.cs

@@ -3,10 +3,10 @@ namespace DateRecurrenceR.Core;
 /// <summary>
 ///     Represents a number of the day of the month
 /// </summary>
-#if NET6_0
-public readonly struct DayOfMonth
-#else
+#if NET8_0_OR_GREATER
 public readonly struct DayOfMonth : IInt32Based<DayOfMonth>
+#else
+public readonly struct DayOfMonth : IEquatable<DayOfMonth>
 #endif
 {
     private const int MinVal = 1;

src/DateRecurrenceR/Core/DayOfYear.cs

@@ -3,10 +3,10 @@ namespace DateRecurrenceR.Core;
 /// <summary>
 ///     Represents a number of the day of the year
 /// </summary>
-#if NET6_0
-public readonly struct DayOfYear
-#else
+#if NET8_0_OR_GREATER
 public readonly struct DayOfYear : IInt32Based<DayOfYear>
+#else
+public readonly struct DayOfYear : IEquatable<DayOfYear>
 #endif
 {
     private const int MinVal = 1;

src/DateRecurrenceR/Core/IInt32Based.cs

@@ -2,11 +2,11 @@
 
 namespace DateRecurrenceR.Core;
 
+#if NET8_0_OR_GREATER
 /// <summary>
 /// 
 /// </summary>
 /// <typeparam name="TSelf"></typeparam>
-#if NET8_0_OR_GREATER
 public interface IInt32Based<TSelf> : IEquatable<TSelf>, IEqualityOperators<TSelf, TSelf, bool>, IMinMaxValue<TSelf>
     where TSelf : IInt32Based<TSelf>;
 #endif

src/DateRecurrenceR/Core/Interval.cs

@@ -3,10 +3,10 @@ namespace DateRecurrenceR.Core;
 /// <summary>
 ///     Represents a number of the interval
 /// </summary>
-#if NET6_0
-public readonly struct Interval
-#else
+#if NET8_0_OR_GREATER
 public readonly struct Interval : IInt32Based<Interval>
+#else
+public readonly struct Interval : IEquatable<Interval>
 #endif
 {
     private const int MinVal = 1;
@@ -27,7 +27,7 @@ public Interval()
     /// </summary>
     public Interval(int value)
     {
-        if (value is < MinVal or > MaxVal) throw new ArgumentOutOfRangeException(nameof(value));
+        if (value < MinVal) throw new ArgumentOutOfRangeException(nameof(value));
 
         _value = value;
     }

src/DateRecurrenceR/Core/MonthOfYear.cs

@@ -3,10 +3,10 @@ namespace DateRecurrenceR.Core;
 /// <summary>
 ///     Represents a number of the month of the year
 /// </summary>
-#if NET6_0
-public readonly struct MonthOfYear
-#else
+#if NET8_0_OR_GREATER
 public readonly struct MonthOfYear : IInt32Based<MonthOfYear>
+#else
+public readonly struct MonthOfYear : IEquatable<MonthOfYear>
 #endif
 {
     private const int MinVal = 1;