remove gigablast website link (website gone, connection refused) (#3738)

- https://www.gigablast.com/ : HTTPSConnectionPool(host='www.gigablast.com', port=443): Max retries exceeded with url: / (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7f2e6cfde740>: Failed to establish a new connection: [Errno 111] Connection refused'))
- ref. https://github.com/awesome-selfhosted/awesome-selfhosted/issues/3558

README.md

@@ -1712,7 +1712,7 @@ Software and tools to help with [enterprise resource and supply planning](https:
 A [search engine](https://en.wikipedia.org/wiki/Search_engine_(computing)) is an [information retrieval system](https://en.wikipedia.org/wiki/Information_retrieval) designed to help find information stored on a computer system. This includes [Web search engines](https://en.wikipedia.org/wiki/Web_search_engine).
 
 - [Fess](https://fess.codelibs.org/) - Fess is a very powerful and easily deployable Enterprise Search Server. ([Demo](https://search.n2sm.co.jp/), [Source Code](https://github.com/codelibs/fess)) `Apache-2.0` `Java/Docker`
-- [Gigablast](https://www.gigablast.com/) - Open-source search engine. ([Source Code](https://github.com/gigablast/open-source-search-engine)) `Apache-2.0` `C++`
+- [Gigablast](https://github.com/gigablast/open-source-search-engine) - Open-source search engine. `Apache-2.0` `C++`
 - [Hound](https://github.com/hound-search/hound) - Lightning fast code searching made easy. `MIT` `Go/Docker`
 - [Jina](https://github.com/jina-ai/jina/) - Cloud-native neural search framework for any kind of data. `Apache-2.0` `Python`
 - [librengine](https://github.com/liameno/librengine) - Private web search engine. `GPL-3.0` `C++`