Add non defer use to context cancelable check

[odk-]

For the normal use of context cancel func like that one:

package main

import (
    "context"
    "time"
)

func main() {
    _, cancelFunc := context.WithTimeout(context.Background(), time.Minute)

    cancelFunc()
}

check is giving a false positive result:

❯ semgrep -f ~/s2b/code/stuff/semgrep-go .
Running 46 rules...

 main.go
     Users.odk.s2b.code.stuff.semgrep-go.cancelable-context-not-systematically-cancelled
        it is good practice to call context cancellation function, cancelFunc(), in any case

          9┆ _, cancelFunc := context.WithTimeout(context.Background(), time.Minute)

skipped: all .gitignored files
for a detailed list of skipped files, run semgrep with the --verbose flag

ran 46 rules on 1 files: 1 findings

This PR adds another case that covers this situation.