Fix syntax error and type mismatch

[intls]

Description

1. Syntax Error - A closing curly brace}is missing in the f-string on line 41. This results in a syntax error because Python expects the expression inside the curly braces to be completed and the quotation marks to be closed.

2. Type Mismatch - The variables TEST, FETCH, and NO_CACHE are initialized using the env_vars function, which returns string values (e.g., "true" or "false"). However, in the ExecConf class, these variables are annotated as bool. Assigning string values to boolean attributes leads to a type mismatch.

If the string values are converted to booleans before assignment, this ensures that the test, fetch, and no_cache attributes will have the bool type, consistent with their annotations.

[sanchitram1]

1. I don't think a } is missing. Your PR adds a ), so it renders right
2. The env_vars function returns boolean values. The purpose was to centrally handle all the different acceptance values (like 1, or true) over there. I think we can add the return type to the function.

[sanchitram1]

@intls – could you also add the return type to the env_vars function in core.utils? I think that might prevent this confusion about the return types for future contributors.