Add SerpApi (#337)

Similar to SearchApi, we offer 100 free credits every month to access all of our APIs.

README.md

@@ -583,6 +583,7 @@
 | [ScreenshotOne.com](https://screenshotone.com/) | Convert URLs, HTML, or Markdown into PNG, JPEG, WebP, or PDF with a simple screenshot API | `apiKey`| Yes | Yes |
 | [SearchApi](https://www.searchapi.io/) | Real-Time Google SERP API | `apiKey` | Yes | No |
 | [Serialif Color](https://color.serialif.com/) | Color conversion, complementary, grayscale and contrasted text | No | Yes | No |
+| [SerpApi](https://serpapi.com/) | Scrape Google and other search engines  | `apiKey` | Yes | No |
 | [Shadify](https://github.com/cheatsnake/shadify) | Service for generating data and executing logic to create various games and puzzles | No | Yes | Yes |
 | [Sheetsu](https://sheetsu.com/) | Easy google sheets integration | `apiKey`| Yes | Unknown |
 | [Sonar](https://github.com/Cgboal/SonarSearch) | Project Sonar DNS Enumeration API | No | Yes | Yes |