Default specifier operator regression from v2023.6.18

[sebastien-coavoux]

Issue description

Describe the issue briefly here.

Look like requirement lib update change the format expected in a Pipfile to specify version requirements

Expected result

Expecting package = "X.Y.Z" to be a valid spec

Actual result

Stack trace with Invalid specifier: '0.95.0'

Steps to replicate

mkdir -p  /tmp/pyenvbug
cd /tmp/pyenvbug/
virtualenv env
. env/bin/activate
echo -e '[packages]\nfastapi = "0.95.0"\n' > Pipfile

pip install pipenv==2023.6.26
pipenv install  # fails with: Invalid specifier: '0.95.0'

pip install pipenv==2023.6.18
pipenv install  # works

deactivate
cd
rm -rf /tmp/pyenvbug

Looking at the code, look like the operator is compulsory so that package = "==X.Y.Z" is the way to specify version requirement

Correct me if I am wrong, but the syntax package = "X.Y.Z" is / was expected to work before, right?

I have a bunch of Pipfile to fix with the "new" syntax if this is the way moving forward.

[matteius]

You are probably right, this is likely a regression. If you see where to patch requirementslib or pipenv for this issue feel free to open a PR against pipenv and we can handle porting the fix over to reqlib -- otherwise I will look into it when I can get some more time.