Fix HttpBadRequestException description

[jsanahuja]

Class Slim\Exception\HttpBadRequestException has a "typo" (a missing space) in $description variable:

Slim/Slim/Exception/HttpBadRequestException.php

Line 26 in 6fbf22f

protected string $description = 'The server cannot or will not process' .

Slim/Slim/Exception/HttpBadRequestException.php

Line 27 in 6fbf22f

'the request due to an apparent client error.';

Using getDescription() to display "generic" responses:

[coveralls]

Coverage: 99.429% (+0.002%) from 99.427% when pulling 591d112 on jsanahuja:fix-http-bad-request-exception-literal into fdf2dab on slimphp:4.x.

[l0gicgate]

Thank you for this contribution @jsanahuja