validate and validate_url shortcuts

[p1c2u]

Deprecates validate_spec and validate_spec_url

[codecov]

Codecov Report

Merging #294 (8564cc6) into master (5f24987) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #294      +/-   ##
==========================================
- Coverage   93.47%   93.45%   -0.03%     
==========================================
  Files          24       24              
  Lines         736      749      +13     
  Branches      106      107       +1     
==========================================
+ Hits          688      700      +12     
  Misses         36       36              
- Partials       12       13       +1     

Files	Coverage Δ
openapi_spec_validator/__init__.py	100.00% <100.00%> (ø)
openapi_spec_validator/__main__.py	88.88% <100.00%> (-0.51%)	⬇️
openapi_spec_validator/shortcuts.py	98.00% <100.00%> (-2.00%)	⬇️
openapi_spec_validator/validation/validators.py	95.52% <ø> (-0.07%)	⬇️