Fix */7 day-of-week step value parsing bug (#191)

* Initial plan

* Initial analysis: Identify issue with */7 cron expression parsing

Co-authored-by: bradymholt <[email protected]>

* Fix */7 day-of-week step value parsing bug

Co-authored-by: bradymholt <[email protected]>

* Rever back to net6.0

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: bradymholt <[email protected]>
Co-authored-by: Brady Holt <[email protected]>

Author: Copilot

lib/ExpressionDescriptor.cs

@@ -580,7 +580,7 @@ Func<string, string> getRangeFormat
       else if (expression.Contains("/"))
       {
         string[] segments = expression.Split('/');
-        description = string.Format(getIntervalDescriptionFormat(segments[1]), getSingleItemDescription(segments[1]));
+        description = string.Format(getIntervalDescriptionFormat(segments[1]), segments[1]);
 
         //interval contains 'between' piece (i.e. 2-59/3 )
         if (segments[0].Contains("-"))

test/TestFormats.en.cs

@@ -367,6 +367,13 @@ public void TestsEvery3DayOfTheWeek()
       Assert.Equal("At 10:15 AM, every 3 days of the week", GetDescription("0 15 10 ? * */3"));
     }
 
+    [Fact]
+    public void TestsEvery7DayOfTheWeek()
+    {
+      // GitHub Issue #188: https://github.com/bradymholt/cron-expression-descriptor/issues/188
+      Assert.Equal("Every hour, every 7 days of the week", GetDescription("0 * * * */7"));
+    }
+
     [Fact]
     public void TestEvery2DayOfTheWeekInRange()
     {