ktor sample - fix CWE-1104

[tomsun28]

Using a deprecated artifact repository may eventually give attackers access for a supply chain attack.

[tomsun28]

Could not find artifact io.ktor:ktor-server-tomcat:jar:1.3.2 in central (https://repo.maven.apache.org/maven2)
so the https://jcenter.bintray.com and https://kotlin.bintray.com/ktor must be there

        <repository>
            <id>repo1</id>
            <url>https://jcenter.bintray.com</url>
            <releases><enabled>true</enabled></releases>
            <snapshots><enabled>true</enabled></snapshots>
        </repository>
        <repository>
            <id>repo2</id>
            <url>https://kotlin.bintray.com/ktor</url>
            <releases><enabled>true</enabled></releases>
            <snapshots><enabled>true</enabled></snapshots>
        </repository>

[tomsun28]

lgtm