added explicit in front of string constructor

7 jobs for issue/quadmath_improvements in 6 minutes and 50 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #53834
duneci
debian:10 clang-6-libcpp-17

00:04:51

passed #53832
duneci iset:avx allowed to fail
debian:10 gcc-7-14--expensive

00:06:48

passed #53833
duneci
debian:10 gcc-8-noassert-17

00:05:45

passed #53836
duneci
debian:9 clang-3.8-14

00:03:34

passed #53835
duneci
debian:9 gcc-6-14

00:05:44

passed #53837
duneci
ubuntu:16.04 gcc-5-14

00:05:13

passed #53838
duneci
ubuntu:18.04 clang-6-17

00:03:57