Incorrect PGN event tag in S15 Glaurung vs Fritz in Bahrain bonus

[skiminki]

The PGN event tag in the master archive PGN is plain and simple "2019". Thus, the event tag in the compiled PGNs is "TCEC Season 15 (18) 2019" which is a bit confusing.

References:

• https://github.com/TCEC-Chess/tcecgames/blob/a0714845d6f0d9304397b914803fa63921712d6c/master-archive/TCEC_Season_Bonus_-_Division_S15_Glaurung_vs_Fritz_in_Bahrain.pgn
• https://tcec-chess.com/#season=bonus&div=s15glaurung_fritzinbahrain&game=1