fix(comp: alert): align icon with text

[liuzaijiang]

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• Docs and demo have been added/updated or not needed

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What kind of change does this PR introduce?

• Bugfix
• Feature
• Component style update
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
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[idux-bot]

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[codecov]

Codecov Report

Merging #881 (ce4e021) into main (d10f5e0) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #881      +/-   ##
==========================================
- Coverage   93.50%   93.45%   -0.05%     
==========================================
  Files         657      657              
  Lines       64594    64954     +360     
  Branches     7845     7821      -24     
==========================================
+ Hits        60396    60706     +310     
- Misses       4198     4248      +50     

Impacted Files	Coverage Δ
...nents/cascader/src/contents/OverlayOptionGroup.tsx	72.41% <0.00%> (-24.02%)	⬇️
...mponents/cascader/src/composables/useSearchable.ts	46.80% <0.00%> (-8.20%)	⬇️
packages/components/checkbox/src/CheckboxGroup.tsx	92.42% <0.00%> (-3.94%)	⬇️
packages/components/menu/src/contents/Utils.tsx	89.65% <0.00%> (-3.21%)	⬇️
packages/cdk/a11y/src/focusMonitor.ts	90.38% <0.00%> (-2.80%)	⬇️
...ges/components/tree-select/src/content/Content.tsx	86.63% <0.00%> (-2.73%)	⬇️
packages/components/dropdown/src/Dropdown.tsx	33.80% <0.00%> (-2.57%)	⬇️
packages/pro/layout/src/Layout.tsx	94.40% <0.00%> (-2.40%)	⬇️
packages/components/date-picker/src/DatePicker.tsx	95.04% <0.00%> (-1.99%)	⬇️
...ges/components/date-picker/src/DateRangePicker.tsx	93.85% <0.00%> (-1.76%)	⬇️
... and 51 more

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