build: use python f-strings

Change-Id: I17695613bb737ac4ba297468c5859ceb18bfdf96
diff --git a/tests/benchmarks/wscript b/tests/benchmarks/wscript
index 73158d8..02ca4f0 100644
--- a/tests/benchmarks/wscript
+++ b/tests/benchmarks/wscript
@@ -5,7 +5,7 @@
 def build(bld):
     for test in bld.path.ant_glob('*.cpp'):
         name = test.change_ext('').path_from(bld.path.get_bld())
-        bld.program(name='test-%s' % name,
+        bld.program(name=f'test-{name}',
                     target=name,
                     source=[test],
                     use='tests-common',