remove additional line from write_file

vlib/os/os.v

@@ -470,7 +470,7 @@ pub fn home_dir() string {
 // write_file writes text data to a file in `path`. 
 pub fn write_file(path, text string) {
 	f := os.create(path)
-	f.writeln(text)
+	f.write(text)
 	f.close()
 }
 

vlib/os/os_test.v

@@ -19,3 +19,15 @@ fn test_unsetenv() {
   assert os.getenv('foo') == ''
 }
 
+fn test_write_and_read_string_to_file() {
+  filename := './test1.txt'
+  hello := 'hello world!'
+  os.write_file(filename, hello)
+  assert hello.len == os.file_size(filename)
+  
+  read_hello := os.read_file(filename) or {
+    panic('error reading file $filename')
+    return
+  }
+  assert hello == read_hello
+}