Fixed circular buffer tests

But there is the problem with mocking Serial.print

src/libs/CircularBuffer.h

@@ -30,8 +30,6 @@ public:
   }
 
   ErrorCode pushBack(const T& item) {
-    Serial.print(_count);
-    Serial.print(_capacity);
     if (_count == _capacity) {
       return ErrorCode::BUFFER_FULL;
     }

test/libs/CircularBuffer_unittest.cpp

@@ -6,7 +6,7 @@ class CircularBufferTest : public ::testing::Test {
 protected:
     void SetUp() override {
         // Initialization code that runs before each test
-        buffer = new CircularBuffer<int>(5); // Create a circular buffer of integers with capacity 5
+        buffer = new CircularBuffer<int>(3); // Create a circular buffer of integers with capacity 5
     }
 
     void TearDown() override {