rust: lock proc-macro2 to maintain MSRV

diff --git a/rust/Cargo.toml.in b/rust/Cargo.toml.in
index fda82e3487e78f354daaef82601a1d8c53494329..62b3e7fedce5ab975bf457e1e8d3dafba01a6274 100644 (file)
--- a/rust/Cargo.toml.in
+++ b/rust/Cargo.toml.in
@@ -48,5 +48,8 @@ data-encoding = "=2.3.3"
 x509-parser = "0.8.2"
 libc = "0.2.67"
 
+# required to keep MSRV supported
+proc-macro2 = "=1.0.65"
+
 [dev-dependencies]
 test-case = "~1.0.1"