Fix conditional compilation of diesel macros

[tomknig]

With 0.11.0-rc1, bcbb48d specifically, a bug was introduced, causing one diesel macro not being excluded from compilation even if the blocking feature is not enabled. The line added in the referenced commit is: https://github.com/ayrat555/fang/blame/2847db35a690f3c58d5e26bb48bf2c1418cf4849/fang/src/lib.rs#L152

The resulting error when trying to compile with

fang = { version = "0.11.0-rc1", features = ["asynk-postgres"], default-features = false }

is:

error: cannot find attribute `diesel` in this scope
   --> /Users/.../.cargo/registry/src/index.crates.io-6f17d22bba15001f/fang-0.11.0-rc1/src/lib.rs:152:3
    |
152 | #[diesel(table_name = fang_tasks)]
    |   ^^^^^^

error: could not compile `fang` (lib) due to 1 previous error
error: Recipe `build-...` failed on line 103 with exit code 101

The solution I suggest is to only include this instance of the diesel macro when the blocking feature is enabled.

[pxp9]

hey , this was fixed in this commit,

f7b5cac#diff-d6910112c105b30683c633451a1ada3fb1ea2671280e13834396a60d9fb70ffdR152

sorry for not review your PR.

[pxp9]

i will close this PR in favor of #157

[tomknig]

No worries; Good, that it has been fixed :)