Update VERSIONs to 3.7-rc1 for release. #182

Job	Run time
build (gcc, 3.12, 3.3)	1m 40s
build (gcc, 3.12, 3.3, test-flags-override)	1m 19s
build (gcc, 3.12, 3.3, test-debug)	2m 13s
build (gcc, 3.12, 3.3, linker-bfd)	1m 45s
build (gcc, 3.12, 3.3, linker-gold)	1m 30s
build (gcc, 3.11, 3.3)	1m 40s
build (gcc, 3.10, 3.3)	1m 30s
build (gcc, 3.9, 3.3)	1m 54s
build (gcc, 3.8, 3.3)	1m 47s
build (gcc, 3.7, 3.3)	1m 43s
build (gcc, pypy3.7, 3.3)	2m 10s
build (gcc, 3.12, 3.2)	1m 35s
build (gcc, 3.12, 3.1)	1m 34s
build (gcc, 3.12, 3.0)	1m 34s
build (gcc, 3.12, 2.7)	1m 43s
build (gcc, 3.12, 2.6)	1m 52s
build (gcc, 3.12, 2.5)	1m 47s
build (clang, 3.12, 3.3)	1m 39s
build (clang, 3.12, 3.3, test-flags-override)	1m 28s
build (clang, 3.12, 3.3, test-debug)	1m 36s
build (clang, 3.11, 3.3)	2m 26s
build (clang, 3.10, 3.3)	1m 44s
build (clang, 3.9, 3.3)	1m 34s
build (clang, 3.8, 3.3)	1m 43s
build (clang, 3.7, 3.3)	1m 45s
build (clang, pypy3.7, 3.3)	2m 5s
build (clang, 3.12, 3.2)	1m 35s
build (clang, 3.12, 3.1)	1m 57s
build (clang, 3.12, 3.0)	2m 10s
build (clang, 3.12, 2.7)	2m 27s
build (clang, 3.12, 2.6)	1m 52s
build (clang, 3.12, 2.5)	1m 57s
build (gcc, 3.12, 3.3, sanitizers)	2m 45s
	59m 59s

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