Add support for BackgroundTasks parameters

[tiangolo]

✨ Add support for BackgroundTasks parameters.

[codecov]

Codecov Report

Merging #103 into master will decrease coverage by 0.03%.
The diff coverage is 98.52%.

@@            Coverage Diff             @@
##           master     #103      +/-   ##
==========================================
- Coverage     100%   99.96%   -0.04%     
==========================================
  Files         113      117       +4     
  Lines        2780     2844      +64     
==========================================
+ Hits         2780     2843      +63     
- Misses          0        1       +1

Impacted Files	Coverage Δ
fastapi/__init__.py	100% <100%> (ø)	⬆️
fastapi/routing.py	100% <100%> (ø)	⬆️
fastapi/dependencies/models.py	100% <100%> (ø)	⬆️
...tutorial/test_background_tasks/test_tutorial002.py	100% <100%> (ø)
fastapi/dependencies/utils.py	100% <100%> (ø)	⬆️
docs/src/background_tasks/tutorial002.py	100% <100%> (ø)
docs/src/background_tasks/tutorial001.py	100% <100%> (ø)
...tutorial/test_background_tasks/test_tutorial001.py	92.85% <92.85%> (ø)
... and 2 more

---

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[codecov]

Codecov Report

Merging #103 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #103    +/-   ##
======================================
  Coverage     100%   100%            
======================================
  Files         113    118     +5     
  Lines        2780   2897   +117     
======================================
+ Hits         2780   2897   +117

Impacted Files	Coverage Δ
fastapi/__init__.py	100% <100%> (ø)	⬆️
fastapi/routing.py	100% <100%> (ø)	⬆️
fastapi/dependencies/models.py	100% <100%> (ø)	⬆️
...tutorial/test_background_tasks/test_tutorial002.py	100% <100%> (ø)
...tutorial/test_background_tasks/test_tutorial001.py	100% <100%> (ø)
fastapi/dependencies/utils.py	100% <100%> (ø)	⬆️
docs/src/background_tasks/tutorial002.py	100% <100%> (ø)
docs/src/background_tasks/tutorial001.py	100% <100%> (ø)
... and 4 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b16ca54...497594a. Read the comment docs.