Upload conan releases to catch2 remote (instead of Catch2)

At some point we moved over to catch2:catchorg (notice lowercase `c`)
instead of Catch2:catchorg, but we kept uploading the released
packages to the upper-cased repository... Time to fix this, and then
merge them again.

.conan/build.py

@@ -31,7 +31,7 @@ def upload(self):
             not match the stable pattern. Otherwise it will upload to stable
             channel.
         """
-        return os.getenv("CONAN_UPLOAD", "https://api.bintray.com/conan/catchorg/Catch2")
+        return os.getenv("CONAN_UPLOAD", "https://api.bintray.com/conan/catchorg/catch2")
 
     @property
     def upload_only_when_stable(self):