[BUGFIX] Add missing imports for @throws annotations (#897)

Author: oliverklee

config/phpstan-baseline.neon

@@ -180,12 +180,6 @@ parameters:
 			count: 1
 			path: ../src/RuleSet/RuleSet.php
 
-		-
-			message: '#^PHPDoc tag @throws with type Sabberworm\\CSS\\Value\\SourceException\|Sabberworm\\CSS\\Value\\UnexpectedEOFException\|Sabberworm\\CSS\\Value\\UnexpectedTokenException is not subtype of Throwable$#'
-			identifier: throws.notThrowable
-			count: 3
-			path: ../src/Value/CSSFunction.php
-
 		-
 			message: '#^Call to an undefined method Sabberworm\\CSS\\OutputFormat\:\:implode\(\)\.$#'
 			identifier: method.notFound

src/Value/CSSFunction.php

@@ -6,6 +6,9 @@
 
 use Sabberworm\CSS\OutputFormat;
 use Sabberworm\CSS\Parsing\ParserState;
+use Sabberworm\CSS\Parsing\SourceException;
+use Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Sabberworm\CSS\Parsing\UnexpectedTokenException;
 
 /**
  * A `CSSFunction` represents a special kind of value that also contains a function name and where the values are the