"pixi add" adds unfulfillable dependency related to pre-release letter suffix

[Vuenc]

Checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pixi, using pixi --version.

Reproducible example

With a new project pixi.toml:

[project]
channels = ["conda-forge"]
name = "pixi-issue-letter"
platforms = ["osx-arm64"]
version = "0.1.0"

[tasks]

[dependencies]

running

pixi add opentelemetry-instrumentation-aiohttp-client

adds the unfulfillable dependency

[dependencies]
opentelemetry-instrumentation-aiohttp-client = ">=0.51b0,<0.51a1"

Then running pixi install yields

Error:   × failed to solve the conda requirements of 'default' 'osx-arm64'
  ╰─▶ Cannot solve the request because of: No candidates were found for opentelemetry-instrumentation-aiohttp-client >=0.51b0,<0.51a1.

Changing the <0.51a1 to <0.51b1 lets the install go through.

Issue description

It seems as if the handling of pre-release alphanumeric suffixes is not handled correctly by pixi add when computing the smallest excluded version.

Expected behavior

The dependency

[dependencies]
opentelemetry-instrumentation-aiohttp-client = ">=0.51b0,<0.51b1"

should be added.