fix: GEO-1129 adjust vue-datepicker style to match other vuetify components

[banders]

Description

Adjusted the style of the vue-datepicker components in the admin tool. It now matches the style of other vuetify components around it.

Fixes # GEO-1129

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• visual inspection

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have already been accepted and merged

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[sonarcloud]

Quality Gate passed for 'Pay Transparency backend-external'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sonarcloud]

Quality Gate passed for 'Pay Transparency Backend'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sonarcloud]

Quality Gate passed for 'Pay Transparency Frontend'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sonarcloud]

Quality Gate passed for 'Pay Transparency doc-gen-service'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sonarcloud]

Quality Gate passed for 'Pay Transparency admin-frontend'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud