Update for new Hugo versions

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

layouts/_partials/seriesnav.html

@@ -0,0 +1,17 @@
+{{- $page := . -}}
+{{- $term := index (.GetTerms "series") 0 -}}
+{{- with $term -}}
+{{- /* No idea why the 'Reverse' is needed? */ -}}
+{{- $pages := (site.Taxonomies.series.Get .Data.Term).Pages.ByDate.Reverse -}}
+<nav class="series-navigation">
+{{- with $pages.Prev $page -}}
+{{- partial "serieslink.html" (dict "direction" "previous" "page" .) -}}
+{{- end -}}
+{{- $nextPage := $pages.Next $page -}}
+{{- if $nextPage -}}
+{{- partial "serieslink.html" (dict "direction" "next" "page" $nextPage) -}}
+{{- else if eq $term.Params.status "ongoing" -}}
+{{- partial "serieslinkplaceholder.html" (dict "direction" "next") -}}
+{{- end -}}
+</nav>
+{{- end -}}