Simplify writing out a literal {}

It's arguably simpler to write a format string that doesn't take
arguments than one with an argument that looks like a format string.

Found by clippy lint write_literal:
https://rust-lang.github.io/rust-clippy/master/index.html#write_literal

1 files changed, 1 insertions, 1 deletions

diff --git a/openpgp/src/regex/lexer.rs b/openpgp/src/regex/lexer.rs
index 18300d90..ec1344ad 100644
--- a/openpgp/src/regex/lexer.rs
+++ b/openpgp/src/regex/lexer.rs
@@ -7,7 +7,7 @@ pub enum LexicalError {
 impl fmt::Display for LexicalError {
     // This trait requires `fmt` with this exact signature.
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", "{}")
+        f.write_str("{}")
     }
 }