Let the spec file be unmodified rust2rpm output

This is possible now that rust2rpm 26.1 can add static BuildRequires
(which are available to be used in %prep).

rust-libdeflater.spec

@@ -14,9 +14,6 @@ URL:            https://crates.io/crates/libdeflater
 Source:         %{crates_source}
 
 BuildRequires:  cargo-rpm-macros >= 24
-# Do downstream crate metadata changes programmatically in %%prep. Since %%prep
-# runs before %%generate_buildrequires, we must add the following manually
-# rather than generating a dynamic BuildRequires via rust2rpm.toml.
 BuildRequires:  tomcli
 
 %global _description %{expand:

rust2rpm.toml

@@ -1,3 +1,8 @@
+[requires]
+build = [
+    "tomcli",
+]
+
 [scripts.prep]
 post = [
     "# Do not depend on criterion; it is needed only for benchmarks.",