fix: 修复了计算器UI 按钮间隔不一致的问题

[moondie]

原issue:
由于原代码的按钮区域大未正确设置，且按钮设置为固定大小，而 QGridLayout会自动调整，导致按钮间隔不一致。 现在略微修改一些Widget和按钮宽度，将按钮大小调整为用setMaximumSize或setMinimumSize设置,使得各模式下按钮布局间隔均一致。
修改前后对比(左图为修改后效果):

标准模式最明显

科学模式

程序员模式

整体布局更加和谐，特别是标准模式、科学模式。

[hundundadi]

Hello, after our internal evaluation, this pr has certain risks and is not suitable for the time being.

[deepin-bot]

TAG Bot

New tag: 6.0.1
DISTRIBUTION: unstable
Suggest: synchronizing this PR through rebase #110

[deepin-bot]

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New tag: 6.0.2
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Suggest: synchronizing this PR through rebase #114

[deepin-bot]

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New tag: 6.5.0
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[deepin-bot]

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New tag: 6.5.1
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Suggest: synchronizing this PR through rebase #117

[deepin-bot]

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New tag: 6.5.2
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Suggest: synchronizing this PR through rebase #118

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New tag: 6.5.3
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Suggest: synchronizing this PR through rebase #120

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New tag: 6.5.4
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[deepin-bot]

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New tag: 6.5.5
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Suggest: synchronizing this PR through rebase #133

[deepin-bot]

TAG Bot

New tag: 6.5.6
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Suggest: synchronizing this PR through rebase #134