V0.7.0rc1: torch.compile, preserve axis identity, array api

Major changes:

• torch.compile just works, registration of operations happens automatically
• JAX's distributed arrays can use ellipses, and in general ellipsis processing now preserves axis identity. This involved changing internal gears of einops.
• Array API: einops operations can be used with any framework that follows the standard (see einops.array_api)
• Python 3.7 is dead. Good bye, you were great at the time
• Gluon is dropped as previously announced
• Reduce/repeat/rearrange all accept lists now

What's Changed

• Support array api by @arogozhnikov in #261
• add type-based caching by @arogozhnikov in #262
• Uniform support for list inputs across rearrange/reduce/repeat by @arogozhnikov in #263
• Drop gluon by @arogozhnikov in #264
• automatically register torch ops in torchdynamo by @arogozhnikov in #265
• release 0.7.0rc1, highlight changes in README by @arogozhnikov in #266
• Preserve axis identity + drop python 3.7 by @arogozhnikov in #255

Full Changelog: v0.6.1...v0.7.0rc1