[MINOR][CORE] Use https for bintray spark-packages repository

## What changes were proposed in this pull request?

This patch changes the schema of url from http to https for bintray spark-packages repository. Looks like we already changed the schema of repository url for pom.xml but missed inside the code.

## How was this patch tested?

Manually ran the `--package` via `./bin/spark-shell --verbose  --packages "RedisLabs:spark-redis:0.3.2"`

```
...
Ivy Default Cache set to: /Users/jlim/.ivy2/cache
The jars for the packages stored in: /Users/jlim/.ivy2/jars
:: loading settings :: url = jar:file:/Users/jlim/WorkArea/ScalaProjects/spark/dist/jars/ivy-2.4.0.jar!/org/apache/ivy/core/settings/ivysettings.xml
RedisLabs#spark-redis added as a dependency
:: resolving dependencies :: org.apache.spark#spark-submit-parent-2fee2e18-7832-4a4d-9e97-7b3d0fef766d;1.0
	confs: [default]
	found RedisLabs#spark-redis;0.3.2 in spark-packages
	found redis.clients#jedis;2.7.2 in central
	found org.apache.commons#commons-pool2;2.3 in central
downloading https://dl.bintray.com/spark-packages/maven/RedisLabs/spark-redis/0.3.2/spark-redis-0.3.2.jar ...
	[SUCCESSFUL ] RedisLabs#spark-redis;0.3.2!spark-redis.jar (824ms)
downloading https://repo1.maven.org/maven2/redis/clients/jedis/2.7.2/jedis-2.7.2.jar ...
	[SUCCESSFUL ] redis.clients#jedis;2.7.2!jedis.jar (576ms)
downloading https://repo1.maven.org/maven2/org/apache/commons/commons-pool2/2.3/commons-pool2-2.3.jar ...
	[SUCCESSFUL ] org.apache.commons#commons-pool2;2.3!commons-pool2.jar (150ms)
:: resolution report :: resolve 4586ms :: artifacts dl 1555ms
	:: modules in use:
	RedisLabs#spark-redis;0.3.2 from spark-packages in [default]
	org.apache.commons#commons-pool2;2.3 from central in [default]
	redis.clients#jedis;2.7.2 from central in [default]
	---------------------------------------------------------------------
	|                  |            modules            ||   artifacts   |
	|       conf       | number| search|dwnlded|evicted|| number|dwnlded|
	---------------------------------------------------------------------
	|      default     |   3   |   3   |   3   |   0   ||   3   |   3   |
	---------------------------------------------------------------------
```

Closes #24061 from HeartSaVioR/MINOR-use-https-to-bintray-repository.

Authored-by: Jungtaek Lim (HeartSaVioR) <[email protected]>
Signed-off-by: Sean Owen <[email protected]>

core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala

@@ -1087,7 +1087,7 @@ private[spark] object SparkSubmitUtils {
     val sp: IBiblioResolver = new IBiblioResolver
     sp.setM2compatible(true)
     sp.setUsepoms(true)
-    sp.setRoot("http://dl.bintray.com/spark-packages/maven")
+    sp.setRoot("https://dl.bintray.com/spark-packages/maven")
     sp.setName("spark-packages")
     cr.add(sp)
     cr