Missing f prefix on f-strings fix

[code-review-doctor]

Fixes #2825

[codecov-commenter]

Codecov Report

Merging #2826 (2e0e618) into master (48e326f) will decrease coverage by 0.75%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #2826      +/-   ##
==========================================
- Coverage   87.36%   86.60%   -0.76%     
==========================================
  Files          94       94              
  Lines       10037    10037              
  Branches     2486     2486              
==========================================
- Hits         8769     8693      -76     
- Misses        802      865      +63     
- Partials      466      479      +13     

Impacted Files	Coverage Δ
vyper/builtin_functions/convert.py	88.21% <0.00%> (-2.29%)	⬇️
vyper/codegen/abi_encoder.py	86.66% <0.00%> (ø)
vyper/codegen/core.py	84.55% <0.00%> (ø)
vyper/semantics/types/function.py	87.10% <0.00%> (ø)
vyper/builtin_functions/functions.py	84.43% <100.00%> (-4.60%)	⬇️
vyper/__init__.py	58.82% <0.00%> (-17.65%)	⬇️
vyper/semantics/types/value/numeric.py	80.45% <0.00%> (-4.60%)	⬇️
vyper/ast/nodes.py	92.59% <0.00%> (-1.63%)	⬇️
... and 3 more

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