Update VERSIONs to 3.7-rc1 for release. #93

Job	Run time
build (gcc, 3.12, 3.3)	1m 31s
build (gcc, 3.12, 3.3, test-flags-override)	1m 27s
build (gcc, 3.12, 3.3, test-debug)	1m 27s
build (gcc, 3.12, 3.3, linker-bfd)	1m 41s
build (gcc, 3.12, 3.3, linker-gold)	1m 47s
build (gcc, 3.11, 3.3)	1m 27s
build (gcc, 3.10, 3.3)	1m 38s
build (gcc, 3.9, 3.3)	1m 40s
build (gcc, 3.8, 3.3)	1m 32s
build (gcc, 3.7, 3.3)	1m 38s
build (gcc, pypy3.7, 3.3)	1m 56s
build (gcc, 3.12, 3.2)	1m 39s
build (gcc, 3.12, 3.1)	1m 29s
build (gcc, 3.12, 3.0)	1m 46s
build (gcc, 3.12, 2.7)	1m 52s
build (gcc, 3.12, 2.6)	1m 42s
build (gcc, 3.12, 2.5)	1m 49s
build (clang, 3.12, 3.3)	1m 41s
build (clang, 3.12, 3.3, test-flags-override)	1m 25s
build (clang, 3.12, 3.3, test-debug)	1m 32s
build (clang, 3.11, 3.3)	1m 36s
build (clang, 3.10, 3.3)	1m 59s
build (clang, 3.9, 3.3)	1m 38s
build (clang, 3.8, 3.3)	1m 46s
build (clang, 3.7, 3.3)	1m 39s
build (clang, pypy3.7, 3.3)	2m 12s
build (clang, 3.12, 3.2)	1m 48s
build (clang, 3.12, 3.1)	1m 36s
build (clang, 3.12, 3.0)	1m 38s
build (clang, 3.12, 2.7)	1m 58s
build (clang, 3.12, 2.6)	1m 55s
build (clang, 3.12, 2.5)	2m 21s
build (gcc, 3.12, 3.3, sanitizers)	1m 58s
	56m 43s

Provide feedback