Fast follow of #1429: fix typo in version specifier (#1431)

Fixes a misplaced single quote.

## Before:

![image](https://github.com/user-attachments/assets/0b73bf65-4802-49bb-a64f-0d46aa2dd250)
We set `VERSION_SPECIFIER='=='${{ env.VERSION }}`, and this evaluates to
`'=='0.98.0rc2`.

Instead, we need it to evaluate to `'==0.98.0rc2'`.

## After:
I can't test this in github actions unless this is merged and deployed,
but I tried to test locally:

![image](https://github.com/user-attachments/assets/8831765c-3073-4823-b89c-2d779b7f62f0)

This PR moves the `'` character to what I think is the correct place for
the version specifier string to be interpreted correctly by pip.

.github/workflows/publish-to-ghcr-and-pypi.yml

@@ -86,4 +86,4 @@ jobs:
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
           # e.g. '==0.98.0'
-          build-args: VERSION_SPECIFIER='=='${{ env.VERSION }}
+          build-args: VERSION_SPECIFIER='==${{ env.VERSION }}'