Add guzzlehttp promises ^2.0.0 as alternate version #92

Job	Run time
build-source	1m 46s
php-xdebug-docker (7.4, 3.1.5)	1m 17s
php-xdebug-docker (8.0, 3.1.5)	59s
php-xdebug-docker (8.1, 3.1.5)	1m 14s
php-xdebug-docker (8.2, 3.2.1)	1m 17s
ci-checks (7.4, --prefer-lowest)	35s
ci-checks (8.0, --prefer-lowest)	33s
confluent-integration (latest)	1m 47s
ci-checks (8.1, --prefer-lowest)	1m 10s
confluent-integration (4.1.4)	59s
ci-checks (8.2, --prefer-lowest)	16s
confluent-integration (5.5.2)	1m 29s
ci-checks (7.4, --prefer-stable)	46s
ci-checks (8.0, --prefer-stable)	21s
ci-checks (8.1, --prefer-stable)	47s
ci-checks (8.2, --prefer-stable)	48s
	16m 4s

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