Update MainlineVersionCalculator.cs

conflict fix

Author: koershov

src/GitVersion.Core/VersionCalculation/MainlineVersionCalculator.cs

@@ -202,7 +202,7 @@ private IBranch GetMainline(ICommit? baseVersionSource)
         /// <returns>The best possible merge base between the current commit and <paramref name="mainline"/> that is not the child of a forward merge.</returns>
         private ICommit FindMergeBaseBeforeForwardMerge(ICommit? baseVersionSource, IBranch mainline, [NotNullWhen(true)] out ICommit? mainlineTip)
         {
-            var mergeBase = repositoryStore.FindMergeBase(context.CurrentCommit, mainline.Tip);
+            var mergeBase = this.repositoryStore.FindMergeBase(context.CurrentCommit, mainline.Tip);
             //var mainlineCommitLog = this.repositoryStore.GetMainlineCommitLog(mergeBase.Parents.FirstOrDefault(), mainline.Tip).ToList();
             var mainlineCommitLog = this.repositoryStore.GetMainlineCommitLog(baseVersionSource, mainline.Tip).ToList();