docs: fix Python snippet casing (#5244)

docs/src/api/python.md

@@ -9,7 +9,7 @@ Terminates this instance of Playwright in case it was created bypassing the Pyth
 >>> playwright = sync_playwright().start()
 
 >>> browser = playwright.chromium.launch()
->>> page = browser.newPage()
+>>> page = browser.new_page()
 >>> page.goto("http://whatsmyuseragent.org/")
 >>> page.screenshot(path="example.png")
 >>> browser.close()