fix: Lowercased country code (#343)

Impacted files:
* `api_saveProduct_test.dart`: unrelated - raised time out for "save" tests
* `CountryHelper.dart`: lowercased the country code for conversions

lib/utils/CountryHelper.dart

@@ -1007,11 +1007,14 @@ extension OpenFoodFactsCoutryExtension on OpenFoodFactsCountry {
 
 /// Helper class around [OpenFoodFactsCountry]
 class CountryHelper {
-  /// Converts an ISO 2 code into an [OpenFoodFactsCountry]
+  /// Converts an ISO 2 code into an [OpenFoodFactsCountry] (case-insensitive).
+  ///
+  /// E.g. 'fr' and 'FR' will give the same result: OpenFoodFactsCountry.FRANCE.
   static OpenFoodFactsCountry? fromJson(String? code) {
     if (code == null) {
       return null;
     }
+    code = code.toLowerCase();
     for (final OpenFoodFactsCountry key in OpenFoodFactsCountry.values) {
       if (key.iso2Code == code) {
         return key;

test/api_saveProduct_test.dart

@@ -85,11 +85,7 @@ void main() {
       );
 
       testProductResult1(result2);
-    },
-        timeout: Timeout(
-          // this guy is rather slow
-          Duration(seconds: 90),
-        ));
+    });
 
     /// Returns a timestamp up to the minute level.
     String _getMinuteTimestamp() =>
@@ -189,11 +185,7 @@ void main() {
 
       expect(frenchGermanResult.product, isNotNull);
       expect(frenchGermanResult.product!.productName, frenchProductName);
-    },
-        timeout: Timeout(
-          // this guy is rather slow
-          Duration(seconds: 90),
-        ));
+    });
 
     test('add new product test 2', () async {
       Product product = Product(
@@ -229,11 +221,7 @@ void main() {
 
       expect(status.status, 1);
       expect(status.statusVerbose, 'fields saved');
-    },
-        timeout: Timeout(
-          // this guy is rather slow
-          Duration(seconds: 90),
-        ));
+    });
 
     test('add new product test 4', () async {
       Product product = Product(
@@ -434,5 +422,9 @@ void main() {
       );
       expect(status.isWrongUsernameOrPassword(), isTrue);
     });
-  });
+  },
+      timeout: Timeout(
+        // some tests can be slow here
+        Duration(seconds: 90),
+      ));
 }