Fix dubbo maven dependency in sentinel-dubbo-demo

[cdfive]

Describe what this PR does / why we need it

Dubbo demo run failure.

Does this pull request fix one issue?

Fixes #530

Describe how you did it

Add dependency that needed for dubbo 2.6.5:
spring-context-support 1.0.2 for AnnotationInjectedBeanPostProcessor, in dubbo-config-spring which is optional.
netty-all 4.1.31.Final for dubbo-qos, in dubbo-qos which is optional.

Remove spring-context as dubbo.jar depends it.

@see
apache/dubbo#2869

Describe how to verify it

Run demo, start FooProviderBootstrap and FooConsumerBootstrap.

Special notes for reviews

Dubbo 2.6.6 may released next week, waiting it release, we can upgrade from 2.6.5 to 2.6.6,
as it fixes UndeclaredThrowableException issue in consumer side when catch Exception.

@see
apache/dubbo#3386

As Dubbo 2.7.0 need JDK1.8, another demo module may be considered in the future.

[codecov-io]

Codecov Report

Merging #534 into master will increase coverage by 0.3%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##             master     #534     +/-   ##
===========================================
+ Coverage     37.69%   37.99%   +0.3%     
- Complexity     1102     1111      +9     
===========================================
  Files           259      259             
  Lines          8174     8177      +3     
  Branches       1113     1115      +2     
===========================================
+ Hits           3081     3107     +26     
+ Misses         4695     4666     -29     
- Partials        398      404      +6

Impacted Files	Coverage Δ	Complexity Δ
...ibaba/csp/sentinel/eagleeye/EagleEyeLogDaemon.java	30.3% <0%> (-15.16%)	6% <0%> (-2%)
...om/alibaba/csp/sentinel/eagleeye/SyncAppender.java	53.57% <0%> (-14.29%)	5% <0%> (-1%)
.../csp/sentinel/slots/block/degrade/DegradeRule.java	55.55% <0%> (-3.97%)	17% <0%> (-1%)
...sentinel/eagleeye/EagleEyeRollingFileAppender.java	28.9% <0%> (-2.32%)	11% <0%> (-1%)
...tinel/slots/block/flow/param/ParamFlowChecker.java	46.98% <0%> (+0.23%)	20% <0%> (+1%)	⬆️
...a/csp/sentinel/slots/statistic/base/LeapArray.java	69.62% <0%> (+3.79%)	25% <0%> (+1%)	⬆️
...a/csp/sentinel/slots/statistic/base/LongAdder.java	31.91% <0%> (+14.89%)	10% <0%> (+6%)	⬆️
...java/com/alibaba/csp/sentinel/log/LoggerUtils.java	66.66% <0%> (+19.99%)	4% <0%> (+2%)	⬆️
...a/csp/sentinel/slots/statistic/base/Striped64.java	60.41% <0%> (+34.37%)	10% <0%> (+5%)	⬆️

---

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 3e4fc7a...8b3ac2f. Read the comment docs.

[sczyh30]

LGTM

[sczyh30]

👍 Thanks!