Vendor updates and library updates

[stikkireddy]

• Bump github.com/stretchr/testify from 1.5.1 to 1.6.1
• Bump github.com/hashicorp/terraform-plugin-sdk from 1.13.0 to 1.13.1
• Bump github.com/Azure/go-autorest/autorest from 0.10.1 to 0.10.2

[codecov-commenter]

Codecov Report

Merging #91 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #91   +/-   ##
=======================================
  Coverage   47.27%   47.27%           
=======================================
  Files          53       53           
  Lines        6815     6815           
=======================================
  Hits         3222     3222           
  Misses       3539     3539           
  Partials       54       54           

Flag	Coverage Δ
#client	76.45% <ø> (ø)
#provider	38.74% <ø> (ø)