fix(vue-renderer): clone options.head before generating meta tags in spa mode

[pimlie]

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

Resolves: #6428

vue-meta mutates the metaInfo object it receives, which could cause issues as in the linked issue.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly. (PR: #)
• I have added tests to cover my changes (if not applicable, please state why)
• All new and existing tests are passing.

[codecov-io]

Codecov Report

Merging #6429 into dev will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##              dev    #6429   +/-   ##
=======================================
  Coverage   95.61%   95.61%           
=======================================
  Files          79       79           
  Lines        2689     2689           
  Branches      694      694           
=======================================
  Hits         2571     2571           
  Misses        101      101           
  Partials       17       17

Flag	Coverage Δ
#e2e	100% <ø> (ø)	⬆️
#fixtures	50.79% <0%> (ø)	⬆️
#unit	92.26% <100%> (ø)	⬆️

Impacted Files	Coverage Δ
packages/vue-renderer/src/renderers/spa.js	87.87% <100%> (ø)	⬆️

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[pi0]

Thanks!