Add compatibility with Symfony 6.4 applications

[javiereguiluz]

I'm updating some Symfony apps to 6.4 (and later, 7.0). Without this change, I can't update the project because of this conflict:

Problem 1
- sentry/sentry-symfony[4.0.0, ..., 4.0.3] require symfony/config ^3.4.43||^4.4.11||^5.0.11 -> found symfony/config[v3.4.43, ..., v3.4.47, v4.4.11, ..., v4.4.44, v5.0.11, ..., v5.4.26] but these were not loaded, likely because it conflicts with another require.
- sentry/sentry-symfony[4.1.0, ..., 4.2.4] require symfony/config ^3.4.44||^4.4.20||^5.0.11 -> found symfony/config[v3.4.44, v3.4.45, v3.4.46, v3.4.47, v4.4.20, ..., v4.4.44, v5.0.11, ..., v5.4.26] but these were not loaded, likely because it conflicts with another require.
- sentry/sentry-symfony[4.2.5, ..., 4.11.0] require symfony/psr-http-message-bridge ^1.2||^2.0 -> found symfony/psr-http-message-bridge[v1.2.0, v1.3.0, v2.0.0, ..., v2.3.1] but these were not loaded, likely because it conflicts with another require.
- Root composer.json requires sentry/sentry-symfony ^4.0 -> satisfiable by sentry/sentry-symfony[4.0.0, ..., 4.11.0].

We should add ||^7.0 too ... but there's already a PR for adding Symfony 7.0 support in tis project (see #761), so let's not do that here.

Thanks!

[ste93cry]

Thanks for submitting this PR, but I'm closing it because it's a duplicate of #750. Until the package is relased as version 6.4, a suggested workaround by other people is to add "symfony/psr-http-message-bridge": "^2.3" to your own composer.json (I haven't tested this myself)