psr/http-message version compatibility

Statically requiring `^1.0` may cause dependency issues; this should be `^1.1 || ^2.0` instead.
https://github.com/GoogleCloudPlatform/functions-framework-php/blob/5b645eedc7508a16481c364e8cd209fb176d3e03/composer.json#L8

For example (with optional switch `-t`):

composer why psr/http-message
google/auth v1.30.0 requires psr/http-message (^1.1||^2.0)
google/cloud-core v1.52.4 requires psr/http-message (^1.0|^2.0)
google/cloud-functions-framework v1.3.0 requires psr/http-message (^1.0)
guzzlehttp/psr7 2.6.1 requires psr/http-message (^1.1 || ^2.0)
psr/http-client 1.0.2 requires psr/http-message (^1.0 || ^2.0)
psr/http-factory 1.0.2 requires psr/http-message (^1.0 || ^2.0)

The error message may be:

You can only install one version of a package, so only one of these can be installed:
psr/http-message[dev-master, 1.0, 1.0.1, 1.1, 2.0, 2.0.x-dev].

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Seen that also library `cloudevents` requires `^1.0.1` statically.

This may or may not be compatible.