bump core for testing/soroban images to v20.1.0 #590

Job	Run time
amd64 / build-stellar-core	17m 51s
amd64 / build-stellar-horizon	2m 25s
amd64 / build-stellar-friendbot	50s
amd64 / build-rs-stellar-xdr	6m 43s
amd64 / build-stellar-soroban-rpc	5m 38s
arm64 / build-rs-stellar-xdr	58m 41s
arm64 / build-stellar-core	1h 11m 56s
arm64 / build-stellar-friendbot	4m 33s
arm64 / build-stellar-horizon	9m 11s
arm64 / build-stellar-soroban-rpc	22m 34s
amd64 / build	4m 29s
amd64 / test (pubnet)	1m 22s
amd64 / test (local)	1m 33s
amd64 / test (local, --enable-soroban-rpc)	1m 46s
amd64 / push-pr	0s
amd64 / push-release	0s
arm64 / build	7m 39s
arm64 / test (pubnet)	1m 14s
arm64 / test (local)	2m 39s
arm64 / test (local, --enable-soroban-rpc)	2m 55s
arm64 / push-pr	0s
arm64 / push-release	0s
manifest / push	0s
complete	1s
	3h 44m 0s

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