fix: encode URI parameter to proxy URI

Closes #326

src/app/modules/hebis/daia-data.provider.spec.ts

@@ -115,7 +115,7 @@ describe('DaiaDataProvider', () => {
       };
 
       expect(daiaDataProvider.getHoldingLink(holding)).toEqual(
-        `${proxyUrl}${available.href}`,
+        `${proxyUrl}${encodeURIComponent(available.href as string)}`,
       );
     });
   });