Remove the severity: fips change label if fips checksum unchanged

Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15229)

.github/workflows/checksums.yml

@@ -41,7 +41,7 @@ jobs:
         run: make update-fips-checksums
         working-directory: ./build-pristine
       - name: make diff-fips-checksums
-        run: make diff-fips-checksums || echo "fips_changed=1" >> $GITHUB_ENV
+        run: make diff-fips-checksums && echo "fips_unchanged=1" >> $GITHUB_ENV || echo "fips_changed=1" >> $GITHUB_ENV
         working-directory: ./build
       - name: set label
         if: ${{ env.fips_changed }}
@@ -55,3 +55,15 @@ jobs:
               repo: context.repo.repo,
               labels: ['severity: fips change']
             })
+      - name: remove label
+        if: ${{ env.fips_unchanged }}
+        uses: actions/github-script@v4
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            github.issues.removeLabel({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              name: 'severity: fips change'
+            })