Add missing England 1921 Census

.gitignore

@@ -18,3 +18,4 @@
 /tests/clover.xml
 /tests/coverage
 /vendor/
+.DS_Store

app/Census/CensusOfEngland.php

@@ -40,6 +40,7 @@ public function allCensusDates(): array
             new CensusOfEngland1891(),
             new CensusOfEngland1901(),
             new CensusOfEngland1911(),
+			new CensusOfEngland1921(),
             new RegisterOfEngland1939(),
         ];
     }

app/Census/CensusOfEngland1921.php

@@ -0,0 +1,58 @@
+<?php
+
+/**
+ * webtrees: online genealogy
+ * Copyright (C) 2023 webtrees development team
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace Fisharebest\Webtrees\Census;
+
+/**
+ * Definitions for a census
+ */
+class CensusOfEngland1921 extends CensusOfEngland implements CensusInterface
+{
+    /**
+     * When did this census occur.
+     *
+     * @return string
+     */
+    public function censusDate(): string
+    {
+        return '19 JUN 1921';
+    }
+
+    /**
+     * The columns of the census.
+     *
+     * @return array<CensusColumnInterface>
+     */
+    public function columns(): array
+    {
+        return [
+			new CensusColumnFullName($this, 'Name', 'Name and surname'),
+			new CensusColumnRelationToHead($this, 'Relation', 'Relationship to head of household'),
+			new CensusColumnAge($this, 'Age', 'Age (Y/M)'),
+			new CensusColumnSexMF($this, 'Sex', 'Male or Female'),
+			new CensusColumnConditionEnglish($this, 'Condition', 'Marriage or Orphanhood'),
+			new CensusColumnBirthPlace($this, 'Birthplace', 'Where born in UK', 'width: 100px;'),
+			new CensusColumnNationality($this, 'Nat', 'Where born if not in UK'),
+			new CensusColumnOccupation($this, 'Occupation', 'Personal Occupation or Schooling', 'width: 100px;'),
+			new CensusColumnNull($this, 'Emp', 'Employment'),
+			new CensusColumnNull($this, 'Work place', 'Place of Work'),
+			new CensusColumnNull($this, 'ChL', 'No. of living children, total and by age'),
+        ];
+    }
+}