Removing unit from `img`'s height attribute for label.icon

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#attr-height

layouts/partials/header.html

@@ -47,7 +47,7 @@
             <a href="{{ "" | absLangURL }}" accesskey="h" title="{{ $label_text }} (Alt + H)">
                 {{- if .Site.Params.label.icon }}
                 <img src="{{- .Site.Params.label.icon | absURL -}}" alt="logo" aria-label="logo"
-                    height="{{- .Site.Params.label.iconHeight | default " 30px" -}}">
+                    height="{{- .Site.Params.label.iconHeight | default "30" -}}">
                 {{- end -}}
                 {{- $label_text -}}
             </a>