Fix some namespace formatting

Why not. :)
Found by clang-tidy.

Change-Id: I99a9cf8efa71c446f5a1ae9c3285d96fe8152915
diff --git a/src/grammars.hpp b/src/grammars.hpp
index a6df5c9..fd01b5b 100644
--- a/src/grammars.hpp
+++ b/src/grammars.hpp
@@ -16,8 +16,7 @@
 #include "path_parser.hpp"
 
 #if BOOST_VERSION <= 107700
-namespace boost::spirit::x3::traits
-{
+namespace boost::spirit::x3::traits {
     // Backport https://github.com/boostorg/spirit/pull/702
     // with instructions from https://github.com/boostorg/spirit/issues/701#issuecomment-946743099
     template <typename... Types, typename T>
diff --git a/src/netconf_access.hpp b/src/netconf_access.hpp
index cee092f..27e54e2 100644
--- a/src/netconf_access.hpp
+++ b/src/netconf_access.hpp
@@ -16,11 +16,9 @@
  *     \brief Implementation of DatastoreAccess for accessing a NETCONF server
  */
 
-namespace libnetconf {
-namespace client {
+namespace libnetconf::client {
 class Session;
 }
-}
 
 class Schema;
 class YangSchema;