use isHeadless variable

tests/test_delete_post.py

@@ -56,7 +56,7 @@ def not_owned_post ():
 def test_delete_post(playwright: Playwright, owned_post, not_owned_post) -> None:
     print(owned_post)
     print(not_owned_post)
-    browser = playwright.chromium.launch(headless=False)
+    browser = playwright.chromium.launch(headless=USE_HEADLESS)
     context = browser.new_context()
     page = context.new_page()
     page.goto(URL)

tests/test_edit_post.py

@@ -55,7 +55,7 @@ def not_owned_post ():
     connection.commit()
 
 def test_edit_post(playwright: Playwright, owned_post, not_owned_post) -> None:
-    browser = playwright.chromium.launch(headless=False)
+    browser = playwright.chromium.launch(headless=USE_HEADLESS)
     context = browser.new_context()
     page = context.new_page()
     page.goto(URL)