*: git.monogon.dev -> source.monogon.dev

This implements T882, setting our (virtual) GOPATH to source.monogon.dev
for this repository.

Test Plan: Refactor, CI only.

X-Origin-Diff: phab/D686
GitOrigin-RevId: c5e2309089948ffc3a98e68e2e0e1cbb157d3a36
diff --git a/metropolis/proto/api/BUILD.bazel b/metropolis/proto/api/BUILD.bazel
index ec40562..993d3dc 100644
--- a/metropolis/proto/api/BUILD.bazel
+++ b/metropolis/proto/api/BUILD.bazel
@@ -14,7 +14,7 @@
 go_proto_library(
     name = "api_go_proto",
     compilers = ["@io_bazel_rules_go//proto:go_grpc"],
-    importpath = "git.monogon.dev/source/nexantic.git/metropolis/proto/api",
+    importpath = "source.monogon.dev/metropolis/proto/api",
     proto = ":api_proto",
     visibility = ["//visibility:public"],
 )
@@ -22,6 +22,6 @@
 go_library(
     name = "go_default_library",
     embed = [":api_go_proto"],
-    importpath = "git.monogon.dev/source/nexantic.git/metropolis/proto/api",
+    importpath = "source.monogon.dev/metropolis/proto/api",
     visibility = ["//visibility:public"],
 )