[Rust] Indicate the anonymous lifetime in set's Display impl. (#1014)

Author: gierlachg

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/rust/RustGenerator.java

@@ -1112,7 +1112,7 @@ private static void generateSingleBitSet(
 
         indent(writer, 0, "impl core::fmt::Debug for %s {\n", bitSetType);
         indent(writer, 1, "#[inline]\n");
-        indent(writer, 1, "fn fmt(&self, fmt: &mut core::fmt::Formatter) -> core::fmt::Result {\n");
+        indent(writer, 1, "fn fmt(&self, fmt: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {\n");
         indent(writer, 2, "write!(fmt, \"%s[", bitSetType);
 
         final StringBuilder builder = new StringBuilder();