Update flower field exercise

Update to add new test case from exercism/problem-specifications#2603.

Author: kahgoh

exercises/practice/flower-field/.meta/tests.toml

@@ -44,3 +44,6 @@ description = "cross"
 
 [dd9d4ca8-9e68-4f78-a677-a2a70fd7a7b8]
 description = "large garden"
+
+[6e4ac13a-3e43-4728-a2e3-3551d4b1a996]
+description = "multiple adjacent flowers"

exercises/practice/flower-field/run_test.v

@@ -165,3 +165,13 @@ fn test_large_garden() {
 	]
 	assert annotate(garden) == expected
 }
+
+fn test_multiple_adjacent_flowers() {
+	garden := [
+		' ** ',
+	]
+	expected := [
+		'1**1',
+	]
+	assert annotate(garden) == expected
+}