chore: tell dependabot to check go deps as well (#472)

Tell dependabot to check go deps as well, this should keep
publiccode-parser-go updated, which is a very important thing to
do.

I'm not sure it's the right syntax, but let's try and see.

Author: bfabio

.github/dependabot.yml

@@ -7,3 +7,8 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
+
+  - package-ecosystem: "gomod"
+    directory: "/src/wasm"
+    schedule:
+      interval: "weekly"