Remove Milestone Date Validation

Closes gh-19526

Signed-off-by: Josh Cummings <3627351+jzheaux@users.noreply.github.com>

.github/workflows/milestone-spring-releasetrain.yml

@@ -1,35 +0,0 @@
-name: Check Milestone
-on:
-  milestone:
-    types: [created, opened, edited]
-env:
-  DUE_ON: ${{ github.event.milestone.due_on }}
-  TITLE: ${{ github.event.milestone.title }}
-permissions:
-  contents: read
-jobs:
-  spring-releasetrain-checks:    
-    name: Check DueOn is on a Release Date
-    runs-on: ubuntu-latest
-    if: ${{ github.repository == 'spring-projects/spring-security' }}
-    permissions:
-      contents: none
-    steps:
-    - name: Print Milestone Being Checked
-      run: echo "Validating DueOn '$DUE_ON' for milestone '$TITLE'"
-    - name: Validate DueOn
-      if: env.DUE_ON != ''
-      run: |
-        export TOOL_VERSION=0.1.1
-        wget "https://repo.maven.apache.org/maven2/io/spring/releasetrain/spring-release-train-tools/$TOOL_VERSION/spring-release-train-tools-$TOOL_VERSION.jar"
-        java -cp "spring-release-train-tools-$TOOL_VERSION.jar" io.spring.releasetrain.CheckMilestoneDueOnMain --dueOn "$DUE_ON" --expectedDayOfWeek MONDAY --expectedMondayCount 3
-  send-notification:
-    name: Send Notification
-    needs: [ spring-releasetrain-checks ]
-    if: ${{ failure() || cancelled() }}
-    runs-on: ubuntu-latest
-    steps:
-      - name: Send Notification
-        uses: spring-io/spring-security-release-tools/.github/actions/send-notification@b92832ecbc7cbe969201e6beafbde0ee400cf095 # v1.0.15
-        with:
-          webhook-url: ${{ secrets.SPRING_SECURITY_CI_GCHAT_WEBHOOK_URL }}