Bump phpstan/phpstan-symfony from 2.0.19 to 2.0.20 (#1034)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

composer.json

@@ -7,7 +7,7 @@
         "phpstan/phpstan-deprecation-rules": "2.0.4",
         "phpstan/phpstan-phpunit": "2.0.16",
         "phpstan/phpstan-strict-rules": "2.0.11",
-        "phpstan/phpstan-symfony": "2.0.19",
+        "phpstan/phpstan-symfony": "2.0.20",
         "spaze/phpstan-disallowed-calls": "4.12.0",
         "sqlftw/sqlftw": "0.1.17",
         "staabm/phpstan-baseline-analysis": "0.13.2",