bug: mark descriptions on strategies as nullable (#4156)

This was omitted by mistake.

Fixes 1-1086

src/lib/openapi/spec/strategy-schema.test.ts

@@ -23,6 +23,14 @@ test('strategySchema', () => {
         validateSchema('#/components/schemas/strategySchema', data),
     ).toBeUndefined();
 
+    // allow null descriptions
+    expect(
+        validateSchema('#/components/schemas/strategySchema', {
+            ...data,
+            description: null,
+        }),
+    ).toBeUndefined();
+
     expect(
         validateSchema('#/components/schemas/strategySchema', {}),
     ).toMatchSnapshot();

src/lib/openapi/spec/strategy-schema.ts

@@ -34,6 +34,7 @@ export const strategySchema = {
         },
         description: {
             type: 'string',
+            nullable: true,
             description: 'A short description of the strategy',
             example: 'Gradual rollout to logged in users',
         },