Migrate to terraform plugin v2

[Etienne-Carriere]

• update terraform plugin sdk from 1.x to 2.x : I updated it because it begans to have some dependencies conflicts with recent version of spf13/afero
• Move Github Action test matrix from go 1.16 => 1.18 to 1.18 => 1.20 : I updated that because recent versions of libraries have syntax not compatible with go 1.16/1.17
• Upgrade all libraries => will cover the different dependabot alert :
  • Closes Bump github.com/hashicorp/go-getter from 1.5.3 to 1.7.0 #36
  • Closes Bump golang.org/x/text from 0.3.5 to 0.3.8 #37
  • Closes Bump golang.org/x/net from 0.0.0-20210326060303-6b1517762897 to 0.7.0 #38
  • Closes Bump golang.org/x/sys from 0.0.0-20210324051608-47abb6519492 to 0.1.0 #39
• Switch package from github.com/Etienne-Carriere/terraform-provider-transloadit to github.com/transloadit/terraform-provider-transloadit