[alpaka] Fix Boost version constraints

[bernhardmgruber]

When I proposed to include the alpaka library in #26812 I added version constraints for alpaka's Boost dependencies. However, it seems that the format for the version I entered was not correct. At least, if I use alpaka as a dependency in a project in manifest mode, I get the following error:

$ cmake -DCMAKE_TOOLCHAIN_FILE=~/dev/vcpkg/scripts/buildsystems/vcpkg.cmake ..
-- Running vcpkg install
Error: No version entry for boost-core at version 1.74. This may be fixed by updating vcpkg to the latest master via `git pull`.
Available versions:
    1.80.0#1
    1.80.0
    1.79.0
    1.78.0
    1.77.0
    1.76.0
    1.75.0
    1.74.0
    1.73.0
    1.72.0
    1.71.0
    1.70.0
    1.69.0
    1.68.0
    1.67.0
    1.66.0

See `vcpkg help versioning` for more information.

Notice that vcpkg says that there is no version 1.74 but the version 1.74.0 is available.

• What does your PR fix?

It (tries to) fix the version constraints for Boost in the alpaka port. Please tell me if it is correct now!

• Which triplets are supported/not supported? Have you updated the CI baseline?

  all, No

• Does your PR follow the maintainer guide?

Yes.

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

Yes

[BillyONeal]

Thanks for the fix!