Refactor Apache Mina SSHd version into a POM property.

Author: garydgregory

pom.xml

@@ -92,6 +92,7 @@
     <httpcore5.version>5.4.2</httpcore5.version>
     <httpclient5.version>5.6.1</httpclient5.version>
     <jackrabbit1.version>1.6.5</jackrabbit1.version>
+    <mina.sshd.version>3.0.0-M2</mina.sshd.version>
     <!-- Don't use jackrabbit2 2.21.x, it's labeled "unstable". -->
     <!-- 2.22.0 requires Java 11. -->
     <jackrabbit2.version>2.20.17</jackrabbit2.version>
@@ -489,12 +490,12 @@
       <dependency>
         <groupId>org.apache.sshd</groupId>
         <artifactId>sshd-core</artifactId>
-        <version>3.0.0-M2</version>
+        <version>${mina.sshd.version}</version>
       </dependency>
       <dependency>
         <groupId>org.apache.sshd</groupId>
         <artifactId>sshd-sftp</artifactId>
-        <version>3.0.0-M2</version>
+        <version>${mina.sshd.version}</version>
       </dependency>
       <dependency>
         <groupId>org.apache.mina</groupId>