update symbiflow-tools to use relative repo

Signed-off-by: Alessandro Comodi <acomodi@antmicro.com>

.gitmodules

diff --git a/.gitmodules b/.gitmodules
index 4be8616..097fcb8 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -6,7 +6,7 @@
 	url = https://github.com/SymbiFlow/python-sdf-timing.git
 [submodule "third_party/symbiflow-tools"]
 	path = third_party/symbiflow-tools
-	url = git@dev.antmicro.com:google-prjuray-tools.git
+	url = https://foss-fpga-tools.googlesource.com/prjuray-tools
 [submodule "third_party/edalize"]
 	path = third_party/edalize
 	url = https://github.com/SymbiFlow/edalize.git