In the nix build, COOLWSD_VERSION_HASH becomes the same as COOLWSD_VERSION, e.g.
`24.04.3.5`.  The web server that serves files from
`/browser/$COOLWSD_VERSION_HASH`, doesn't expect the hash to contain dots.

--- a/wsd/FileServer.cpp
+++ b/wsd/FileServer.cpp
@@ -933,7 +933,7 @@ std::string FileServerRequestHandler::getRequestPathname(const HTTPRequest& requ
 
     std::string path(requestUri.getPath());
 
-    Poco::RegularExpression gitHashRe("/([0-9a-f]+)/");
+    Poco::RegularExpression gitHashRe("/([0-9a-f.]+)/");
     std::string gitHash;
     if (gitHashRe.extract(path, gitHash))
     {