Correct the file permission

As title, it seems that some files don't have correct file permissions.

For example, we can see the following command output:

$ ls -al
total 104
drwxrwxr-x   6 lee lee  4096 Oct  4 09:50 ./
drwx------ 554 lee lee 36864 Oct  4 09:50 ../
-rw-rw-r--   1 lee lee  3346 Oct  4 09:50 CODE_OF_CONDUCT.md
-rwxrwxr-x   1 lee lee   792 Oct  4 09:50 composer.json*
-rw-rw-r--   1 lee lee  4724 Oct  4 09:50 CONTRIBUTING.md
drwxrwxr-x   8 lee lee  4096 Oct  4 09:50 .git/
drwxrwxr-x   3 lee lee  4096 Oct  4 09:50 .github/
-rwxrwxr-x   1 lee lee    53 Oct  4 09:50 .gitignore*
-rwxrwxr-x   1 lee lee  1076 Oct  4 09:50 LICENSE.md*
-rw-rw-r--   1 lee lee   563 Oct  4 09:50 phpcs.xml
-rwxrwxr-x   1 lee lee   499 Oct  4 09:50 phpunit.xml*
-rw-rw-r--   1 lee lee   444 Oct  4 09:50 psalm.xml
-rw-rw-r--   1 lee lee  3870 Oct  4 09:50 README.md
drwxrwxr-x   3 lee lee  4096 Oct  4 09:50 src/
drwxrwxr-x   4 lee lee  4096 Oct  4 09:50 tests/
-rw-rw-r--   1 lee lee   251 Oct  4 09:50 .travis.yml

ls tests/CLI/ -al 
drwxrwxr-x 2 lee lee 4096 Oct  4 09:57 ./
drwxrwxr-x 4 lee lee 4096 Oct  4 09:57 ../
-rwxrwxr-x 1 lee lee 7681 Oct  4 09:57 CLITest.php*
-rwxrwxr-x 1 lee lee 3445 Oct  4 09:57 ConsoleTest.php*
-rwxrwxr-x 1 lee lee 1764 Oct  4 09:57 TaskTest.php*

As we can see, composer.json, .gitignore, LICENSE.md and phpunit.xml files should not have executable permission.

And some PHP files in the tests/CLI folder also have the same issue.

And they should be fixed.

Start by checking the tracked modes with ls -l for composer.json, .gitignore, LICENSE.md, phpunit.xml, and the PHP files under tests/CLI. Compare those modes with the other non-executable project files, then verify that the listed files no longer have executable permission.