Revert incorrect copyright attribution for non-contributed files

- In commit b3facaa6bb, the copyright header was
  updated to include "Citron Homebrew Project" across multiple files, regardless
  of whether any contributions were made.

- This commit removes the incorrect attribution and reverts the copyright header
  to its previous state.

- Copyright attribution should only be added when meaningful contributions have
  been made to the file.

- This commit ensures proper compliance with copyright standards and maintains
  correct attribution to the respective contributors.

- Special thanks to Tachi for pointing out the need for these corrections and
  ensuring that proper attribution practices are followed.

src/core/hle/service/nim/nim.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project & 2025 citron Homebrew Project
+// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <chrono>