Fix/clarify CITATION.cff validation

I decided to make a few decisions on this:
1. I decided to only validate on Rust releases. This has a few benefits:
   1. It simplifies choosing some of the values. I'm already asserting that
      the version in the citation file is the Rust Lace version, so this
      makes that association clearer
   2. It makes it easier to know how to validate certain fields. Since
      we release Python and Rust separately, but often on the same day,
      some of the date checking logic is a bit convoluted, since you might
      sometimes have a previous "release" which still was released on
      the same day. Only validating on Rust releases solves that problem
      (unless for some reason we release the Rust version twice
       on the same day, like in a bug fix or something)
2. I decided not to try to make this a pre-requistie for releasing.
   Right now this check runs on releases but does not prevent release
   when it fails. It would be possible to do that but it would require
   either moving this to the `rust-build-test` workflow or a re-design
   of that release workflow, and I think the effort would be better
   spent re-desiging the release workflow to match our current
   branch-based release process. So I'll hold off until we change
   our release process, if we do so.

.github/workflows/citation.yaml

@@ -5,7 +5,6 @@ on:
   push:
     tags:
       - rust-*
-      - python-*
 
 jobs:
     Validate-CITATION-cff:
@@ -33,7 +32,10 @@ jobs:
 
             - name: Verify CITATION.cff date field
               run: |
-                LAST_RELEASE=$(git describe --abbrev=0  --match="rust-*" --match="python-*" HEAD~1)
+                LAST_RELEASE=$(git describe --abbrev=0  --match="rust-*" HEAD~1)
+                echo $LAST_RELEASE
                 LAST_RELEASE_DATE=$(git cat-file -p $LAST_RELEASE:CITATION.cff | cffconvert -f schema.org | jq -r .datePublished)
                 CURRENT_RELEASE_DATE=$(cffconvert -f schema.org | jq -r .datePublished)
-                [[ ! "$CURRENT_RELEASE_DATE" < "$LAST_RELEASE_DATE" ]]
+                echo $CURRENT_RELEASE_DATE $LAST_RELEASE_DATE
+                # Verify that the release date was updated since the last release
+                [[ "$CURRENT_RELEASE_DATE" > "$LAST_RELEASE_DATE" ]]