fix t/010_internals/008_files.t

[skaji]

https://www.cpantesters.org/cpan/report/694c1696-3809-11ec-8d11-e947f7ad8bd4

    #   Failed test 'auto reload 1'
    #   at t/010_internals/008_files.t line 74.
    #          got: 'Hello, Perl world!
    # '
    #     expected: 'Hi, Perl.
    # '

    #   Failed test 'auto reload 2'
    #   at t/010_internals/008_files.t line 74.
    #          got: 'Hello, Perl world!
    # '
    #     expected: 'Hi, Perl.
    # '
    # Looks like you failed 2 tests of 3.

#   Failed test 'cache => 1 (default mode)'
#   at t/010_internals/008_files.t line 75.
# Looks like you failed 1 test of 3.
t/010_internals/008_files.t ..................... 
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/3 subtests 

Currently we use $^T + 10 to update file modification time,
but if the test take a lot of time for some reasons, then $^T + 10 may not update file modification time.

Use time + 10 to make sure we update file modification time.

[skaji]

@syohex Thanks!