[BUG] Restart fails when reading integer time variable

[LudwigBoess]

describe the bug
The restart fails when meta-<step>.toml contains an integer for the time variable.
E.g.:

[metadata]
  time = 163750

This is caused by this line when time has a value of e.g. time = 163750.0.

code version
This happens on the current master branch, last commit: fdbc26a.

compiler/library versions
Happens on Aurora with these modules, but can be reproduced on other systems:

Currently Loaded Modules:
  1) gcc-runtime/13.3.0-ghotoln (H)   7) libxml2/2.13.5
  2) gmp/6.3.0-mtokfaw          (H)   8) hwloc/2.12.1-level-zero
  3) mpfr/4.2.1-gkcdl5w         (H)   9) mpich/opt/develop-git.6037a7a
  4) mpc/1.3.1-rdrlvsl          (H)  10) libfabric/1.22.0
  5) gcc/13.3.0                      11) cray-pals/1.8.0
  6) oneapi/release/2025.2.0         12) cray-libpals/1.8.0

cmake configuration command
cmake -B build -D pgen=streaming -D precision=single -D deposit=zigzag -D shape_order=1 -D mpi=ON -D gpu_aware_mpi=OFF -D output=ON -DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx