Use url-safe characters in falco version

In some cases, you might want to host falco packages in a way where
they're directly accessible via http. The '+' character that separates
the version and the git hash ends up breaking naive solutions that don't
properly url-escape the package name before doing the http fetch.

Of course, clients can properly url-escape, but switching to a tilde is
url safe and I think still preserves the idea of separating the version
and hash.

Signed-off-by: Mark Stemm <mark.stemm@gmail.com>

cmake/modules/GetFalcoVersion.cmake

@@ -27,7 +27,7 @@ if(NOT FALCO_VERSION)
       set(FALCO_VERSION "0.0.0")
     endif()
     # Format FALCO_VERSION to be semver with prerelease and build part
-    string(REPLACE "-g" "+" FALCO_VERSION "${FALCO_VERSION}")
+    string(REPLACE "-g" "~" FALCO_VERSION "${FALCO_VERSION}")
   else()
     # A tag has been found: use it as the Falco version
     set(FALCO_VERSION "${FALCO_TAG}")