feat: add protobuf

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/flux-releaser/schemas/proto/flux_releaser.proto

@@ -0,0 +1,18 @@
+syntax = "proto3";
+
+package flux_releaser;
+
+service Greeter {
+  // Sends a greeting
+  rpc SayHello (HelloRequest) returns (HelloReply) {}
+}
+
+// The request message containing the user's name.
+message HelloRequest {
+  string name = 1;
+}
+
+// The response message containing the greetings.
+message HelloReply {
+  string message = 1;
+}