revert: update deprecated properties

This reverts commit 152763d9ed.

hugo.toml

@@ -1,5 +1,5 @@
 baseURL = 'https://hazemkrimi.tech'
-locale = 'en'
+languageCode = 'en'
 title = 'Hazem Krimi'
 [pagination]
     pagerSize = 5

layouts/_default/home.rss.xml

@@ -44,7 +44,7 @@
     <link>{{ .Permalink }}</link>
     <description>Hazem Krimi's projects and blog</description>
     <generator>Hugo -- gohugo.io</generator>
-    <language>{{ site.Language.Locale }}</language>{{ with $authorEmail }}
+    <language>{{ site.Language.LanguageCode }}</language>{{ with $authorEmail }}
     <managingEditor>{{.}}{{ with $authorName }} ({{ . }}){{ end }}</managingEditor>{{ end }}{{ with $authorEmail }}
     <webMaster>{{ . }}{{ with $authorName }} ({{ . }}){{ end }}</webMaster>{{ end }}{{ with .Site.Copyright }}
     <copyright>{{ . }}</copyright>{{ end }}{{ if not .Date.IsZero }}