Update INSTALL.md: remove deprecated git:// URL

RaineEkman · web-flow · commit 7d0fe9e9a384 · 2023-02-17T13:07:37.000+02:00
The git:// protocol stopped working almost a year ago: https://github.blog/2021-09-01-improving-git-protocol-security-github/
diff --git a/INSTALL.md b/INSTALL.md
@@ -235,7 +235,7 @@ changes.
 
 ```bash
 cd ${HOME}/dev/cpp
-git clone git://github.com/qgis/QGIS.git
+git clone https://github.com/qgis/QGIS.git
 ```
 
 2. Developer Checkout
