fix: Only import pdftotext if installed (Fixes #1419)

* fixes #1419

Author: anthonyharrison

test/test_output_engine.py

@@ -13,7 +13,6 @@
 import unittest
 from datetime import datetime
 
-import pdftotext
 from rich.console import Console
 
 from cve_bin_tool.output_engine import OutputEngine, output_csv, output_json, output_pdf
@@ -478,6 +477,8 @@ def test_output_csv(self):
     )
     def test_output_pdf(self):
         """Test formatting output as PDF"""
+        import pdftotext
+
         output_pdf(self.MOCK_PDF_OUTPUT, False, 1, "cve_test.pdf", False)
         with open("cve_test.pdf", "rb") as f:
             pdf = pdftotext.PDF(f)