Bump scale-encode and scale-decode

[jsdw]

With the improved error handling in scale-encode and scale-decode, this PR bumps the versions of those and removed now-unnecessary code.

Works locally, but won't pass CI until scale-encode and scale-decode have been released with these changes.

Part of a series:

• Improve error handling + consistency when no_std scale-decode#31
• Improve error handling + consistency when no_std scale-encode#13
• You are here: Bump scale-encode and scale-decode #40

Changes tested against Subxt; I'll update that next.

[jsdw]

This should work once paritytech/scale-decode#33 and paritytech/scale-encode#17 are released