Add @XSAM and @dmathieu as repository maintainers #12000

Job	Run time
test-race	3m 51s
compatibility-test (~1.22.4, ubuntu-latest, 386)	2m 10s
test-coverage	4m 19s
compatibility-test (~1.22.4, ubuntu-latest, amd64)	2m 14s
integration (test-mongo-driver)	13s
compatibility-test (~1.22.4, macos-latest, amd64)	44s
lint	4m 59s
compatibility-test (~1.22.4, windows-latest, 386)	7m 55s
compatibility-test (~1.22.4, windows-latest, amd64)	3m 35s
compatibility-test (~1.21.12, ubuntu-latest, 386)	2m 37s
compatibility-test (~1.21.12, ubuntu-latest, amd64)	2m 45s
compatibility-test (~1.21.12, macos-latest, amd64)	3m 10s
compatibility-test (~1.21.12, windows-latest, 386)	6m 55s
compatibility-test (~1.21.12, windows-latest, amd64)	6m 33s
test-integration	1s
test-compatibility	1s
	52m 2s

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