Tamper under Drupal 9

Hi,
I installed Feed 3.0.0-alpha9 and wanted to install tamper in an Drupal 9.1 instance.

After trying this with composer I get this error:
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./composer.sh require 'drupal/feeds_tamper:^2.0@beta'
./composer.json has been updated
Running composer update drupal/feeds_tamper
Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.

Problem 1
- drupal/feeds_tamper 2.0.0-beta1 requires drupal/core ^8.5.0 -> found drupal/core[8.5.0, ..., 8.9.11] but the package is fixed to 9.1.0 (lock file version) by a partial update and that version does not match. Make sure you list it as an argument for the update command.
- drupal/feeds_tamper 2.0.0-beta2 requires drupal/tamper ~1.0 -> found drupal/tamper[dev-1.x, 1.0.0-alpha1, 1.0.0-alpha2, 1.x-dev (alias of dev-1.x)] but it does not match your minimum-stability.
- Root composer.json requires drupal/feeds_tamper ^2.0@beta -> satisfiable by drupal/feeds_tamper[2.0.0-beta1, 2.0.0-beta2].

Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.
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can anybody help here ?

thanks!