Move py-cachetools to src folder am: c9b01f8f0f am: e0f6cd8182

Original change: https://android-review.googlesource.com/c/platform/external/python/cachetools/+/2219104

Change-Id: I9acbb1ceb4b7591e7e715c45ce29c1d436e94a86
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>