Pin K8s version in Kind config

[mzur]

The Helm chart of v0.8 requires K8s <1.22.0 which will break with the most recent version of kindest/node.

References: https://github.com/reanahub/reana/blob/ed48d7eedf92ff64683a2436c890aa49df70f056/helm/reana/Chart.yaml#L31

[codecov-commenter]

Codecov Report

Merging #649 (0ca9993) into maint-0.8 (ed48d7e) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff             @@
##           maint-0.8     #649   +/-   ##
==========================================
  Coverage      19.34%   19.34%           
==========================================
  Files             26       26           
  Lines           2078     2078           
==========================================
  Hits             402      402           
  Misses          1676     1676