v1.21.0

Changes

• Add missing events @jriddle-linode (#365)
• Add account_betas to support customer enrolled beta programs @yec-akamai (#360)
• Add betas to support self serve beta program @yec-akamai (#356)
• Make environmental variable LINODE_URL configurable @zliang-akamai (#359)

Tests

• Fix list volume test @zliang-akamai (#361)
• Change go version to be stable in test CI @zliang-akamai (#357)

Dependencies

• Bump golang.org/x/net from 0.13.0 to 0.14.0 @dependabot (#354)