Fix all fortitude C121 issues

[awvwgk]

use without only list

Details

src/dftd3/api.f90:40:4: C121 'use' statement missing 'only' clause
   |
38 |    use dftd3_utils, only : wrap_to_central_cell
39 |    use dftd3_version, only : get_dftd3_version
40 |    use iso_c_binding
   |    ^^^^^^^^^^^^^^^^^ C121
41 |    use mctc_env, only : wp, error_type, fatal_error
42 |    use mctc_io_structure, only : structure_type, new
   |

src/dftd3/model.f90:19:4: C121 'use' statement missing 'only' clause
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17 | module dftd3_model
18 |    use dftd3_data, only : get_r4r2_val, get_vdw_rad
19 |    use dftd3_reference
   |    ^^^^^^^^^^^^^^^^^^^ C121
20 |    use ieee_arithmetic, only : ieee_is_nan
21 |    use mctc_data, only : get_covalent_rad
   |

test/unit/test_dftd3.f90:18:4: C121 'use' statement missing 'only' clause
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17 | module test_dftd3
18 |    use dftd3
   |    ^^^^^^^^^ C121
19 |    use mctc_env, only : wp
20 |    use mctc_env_testing, only : new_unittest, unittest_type, error_type, check, &
   |

test/unit/test_gcp.f90:19:4: C121 'use' statement missing 'only' clause
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17 | module test_gcp
18 |    use dftd3_cutoff, only : realspace_cutoff
19 |    use dftd3_gcp
   |    ^^^^^^^^^^^^^ C121
20 |    use dftd3_output, only : ascii_gcp_param
21 |    use mctc_env, only : wp
   |

test/unit/test_model.f90:21:4: C121 'use' statement missing 'only' clause
   |
19 |    use dftd3_cutoff, only : get_lattice_points
20 |    use dftd3_data, only : get_vdw_rad, get_r4r2_val
21 |    use dftd3_model
   |    ^^^^^^^^^^^^^^^ C121
22 |    use mctc_data, only : get_covalent_rad
23 |    use mctc_env, only : wp
   |

test/unit/test_pairwise.f90:18:4: C121 'use' statement missing 'only' clause
   |
17 | module test_pairwise
18 |    use dftd3
   |    ^^^^^^^^^ C121
19 |    use mctc_env, only : wp
20 |    use mctc_env_testing, only : new_unittest, unittest_type, error_type, check, &
   |

test/unit/test_param.f90:18:4: C121 'use' statement missing 'only' clause
   |
17 | module test_param
18 |    use dftd3
   |    ^^^^^^^^^ C121
19 |    use mctc_env, only : wp
20 |    use mctc_env_testing, only : new_unittest, unittest_type, error_type, check, &
   |

test/unit/test_periodic_1d.f90:18:4: C121 'use' statement missing 'only' clause
   |
17 | module test_periodic_1d
18 |    use dftd3
   |    ^^^^^^^^^ C121
19 |    use mctc_env, only : wp
20 |    use mctc_env_testing, only : new_unittest, unittest_type, error_type, check, &
   |

test/unit/test_periodic_2d.f90:18:4: C121 'use' statement missing 'only' clause
   |
17 | module test_periodic_2d
18 |    use dftd3
   |    ^^^^^^^^^ C121
19 |    use mctc_env, only : wp
20 |    use mctc_env_testing, only : new_unittest, unittest_type, error_type, check, &
   |

test/unit/test_periodic_3d.f90:18:4: C121 'use' statement missing 'only' clause
   |
17 | module test_periodic_3d
18 |    use dftd3
   |    ^^^^^^^^^ C121
19 |    use mctc_env, only : wp
20 |    use mctc_env_testing, only : new_unittest, unittest_type, error_type, check, &
   |

test/unit/test_periodic_atm.f90:18:4: C121 'use' statement missing 'only' clause
   |
17 | module test_periodic_atm
18 |    use dftd3
   |    ^^^^^^^^^ C121
19 |    use mctc_env, only : wp
20 |    use mctc_env_testing, only : new_unittest, unittest_type, error_type, check, &
   |

test/unit/test_regression.f90:18:4: C121 'use' statement missing 'only' clause
   |
17 | module test_regression
18 |    use dftd3
   |    ^^^^^^^^^ C121
19 |    use mctc_env, only : wp
20 |    use mctc_env_testing, only : new_unittest, unittest_type, error_type, check, &