[gardener-extension-os-gardenlinux]

Improvements

[OPERATOR] The golang has been upgraded to 1.15.5. (#21, @vpnachev)
[OPERATOR] The alpine base image has been upgraded to 3.12.1. (#21, @vpnachev)
[OPERATOR] The cache for Secrets is now disabled to decrease the extension controller's memory footprint (#19, @ialidzhikov)
[OPERATOR] Adds priority class for extension pods to prevent preemption. (#17, @danielfoehrKn)
[DEVELOPER] github.com/gardener/gardener dependency is now updated to v1.12.4. (#18, @ialidzhikov)

gardener-extension-os-gardenlinux: eu.gcr.io/gardener-project/gardener/extensions/os-gardenlinux:v0.7.0