fix GTFS reference date for time period begin #1990

Job	Run time
formatting	1m 12s
api-docs	25s
rsl-ui-checks	1m 18s
macos (macos-x86_64, macos-x86_64-avx)	40m 4s
linux (linux-amd64-avx2-release, linux-amd64)	3m 38s
linux (linux-amd64-noavx-release, linux-amd64-noavx)	3m 42s
macos (macos-x86_64-noavx2, macos-x86_64-noavx, On)	49m 57s
linux (linux-x86-release, linux-x86)	3m 39s
linux (linux-arm-release, linux-arm, qemu-arm-static)	3m 53s
macos (macos-arm64, macos-arm64)	1h 9m 20s
linux (linux-arm64-release, linux-arm64, qemu-aarch64-static)	3m 49s
linux (clang-tidy, true, true)	7m 4s
linux (linux-debug, true, valgrind --leak-check=full --error-exitcode=1)	1m 7s
full-data-set-test	0s
docker	0s
	3h 9m 8s

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