Apply suggestions from code review

Co-authored-by: Paolo Tranquilli <redsun82@github.com>

swift/xcode-autobuilder/XcodeProjectParser.cpp

@@ -257,7 +257,7 @@ static std::unordered_map<std::string, std::vector<std::string>> collectWorkspac
   // Collect all projects not belonging to any workspace into a separate empty bucket
   for (auto& path : projectFiles.xcodeFiles) {
     if (path.extension() == ".xcodeproj") {
-      if (projectsBelongingToWorkspace.count(path.string())) {
+      if (projectsBelongingToWorkspace.contains(path.string())) {
         continue;
       }
       workspaces[std::string()].push_back(path.string());

swift/xcode-autobuilder/xcode-autobuilder.cpp

@@ -80,7 +80,7 @@ static bool autobuild(const CLIArgs& args) {
     return false;
   } else if (!structure.xcodeEncountered && swiftPackages.empty()) {
     DIAGNOSE_ERROR(noProjectFound,
-                   "`autobuild` could not detect an Xcode project or workspace or Swift package");
+                   "`autobuild` detected neither an Xcode project or workspace, nor a Swift package");
     return false;
   } else if (!xcodeTargets.empty()) {
     LOG_INFO("Building Xcode target: {}", xcodeTargets.front());