fix: fix faulty project-path when parsing under linux

the directories in the solution are usually separated using backwards-slashes ('\')
under linux, the path of the solution-file (using forward-slashes ('/')) is combined
with the path that is used in the solution itself. Resulting in something like
'/some/path/to\project.csproj', resulting in a faulty path, which leads to other problems

src/SlnParser/Helper/ProjectDefinitionParser.cs

@@ -43,6 +43,10 @@ public bool TryParseProjectDefinition(
             if (solutionDirectory == null)
                 throw new UnexpectedSolutionStructureException("Solution-Directory could not be determined");
 
+            // NOTE: the path to the project-file is usually separated using '\' - this does not work under linux
+            projectPath = projectPath.Replace('/', Path.DirectorySeparatorChar);
+            projectPath = projectPath.Replace('\\', Path.DirectorySeparatorChar);
+
             var projectFileCombinedWithSolution = Path.Combine(solutionDirectory, projectPath);
             var projectFile = new FileInfo(projectFileCombinedWithSolution);