Bump elliptic-curve dependency to v0.8; ecdsa to v0.10

[tarcieri]

No description provided.

[codecov-io]

Codecov Report

Merging #260 (83a8290) into master (f1324cc) will increase coverage by 0.01%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master     #260      +/-   ##
==========================================
+ Coverage   58.35%   58.37%   +0.01%     
==========================================
  Files          29       29              
  Lines        3823     3829       +6     
==========================================
+ Hits         2231     2235       +4     
- Misses       1592     1594       +2     

Impacted Files	Coverage Δ
k256/src/arithmetic/affine.rs	89.24% <66.66%> (-0.76%)	⬇️
p256/src/arithmetic/affine.rs	91.57% <66.66%> (-0.82%)	⬇️

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