This commit adds copyright attributions in SPDX to the files for matrix-cactus-comments and matrix-cactus-comments-client, following REUSE's specification.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

This commit adds copyright attributions in SPDX format to the files for matrix-bridge-wechat following REUSE's specification.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>