[ci] enable dependabot for vtr

.github/dependabot.yml

@@ -21,3 +21,5 @@ updates:
       - dependency-name: "yosys-plugins"
       # Enable for the yosys submodule
       - dependency-name: "yosys"
+      # Enable for the vtr submodule
+      - dependency-name: "vtr-verilog-to-routing"

vtr-verilog-to-routing

@@ -1 +1 @@
-Subproject commit 5226096ee94b2b589078926a203fe71996343992
+Subproject commit 2f1bfd32080e81c63b0ea3116fbafff2f085202e