Your requirements could not be resolved to an installable set of packages.
Problem 1
- Root composer.json requires phpstan/phpstan ^1.1***.47, ^2.1.6, found phpstan/phpstan[dev-renovate/major-github-actions, ..., dev-php-parser-5, ***.1, ..., ***.12.x-dev, 1.***.***, ..., 1.12.x-dev, 2.***.***, ..., 2.1.x-dev] but it does not match the constraint.
Problem 2
- Root composer.json requires mglaman/phpstan-drupal ^1.2.1 -> satisfiable by mglaman/phpstan-drupal[1.2.1, ..., 1.x-dev].
- mglaman/phpstan-drupal[1.2.1, ..., 1.2.5] require phpstan/phpstan ^1.1***.1 -> found phpstan/phpstan[1.1***.1, ..., 1.12.x-dev] but it conflicts with your root composer.json require (^1.1***.47, ^2.1.6).
- mglaman/phpstan-drupal[1.2.11, ..., 1.x-dev] require phpstan/phpstan ^1.1***.56 -> found phpstan/phpstan[1.1***.56, ..., 1.12.x-dev] but it conflicts with your root composer.json require (^1.1***.47, ^2.1.6).
Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.