Restrict single payment resolving

[NyanKiyoshi]

Fix a missing permission check.

Pull Request Checklist

1. Privileged views and APIs are guarded by proper permission checks.
2. All visible strings are translated with proper context.
3. All data-formatting is locale-aware (dates, numbers, and so on).
4. Database queries are optimized and the number of queries is constant.
5. Database migration files are up to date.
6. The changes are tested.
7. The code is documented (docstrings, project documentation).
8. GraphQL schema and type definitions are up to date.
9. Changes are mentioned in the changelog.

[codecov]

Codecov Report

Merging #4009 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #4009   +/-   ##
=======================================
  Coverage   91.27%   91.27%           
=======================================
  Files         275      275           
  Lines       14953    14953           
  Branches     1448     1448           
=======================================
  Hits        13649    13649           
  Misses        913      913           
  Partials      391      391

Impacted Files	Coverage Δ
saleor/graphql/payment/schema.py	100% <100%> (ø)	⬆️

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