Update ELK images

elasticsearch:
- https://github.com/docker-library/elasticsearch/commit/6f143ea: Update to 7.6.1
- https://github.com/docker-library/elasticsearch/commit/aafce2f: Update to 6.8.7

logstash:
- https://github.com/docker-library/logstash/commit/1bd7995: Update to 7.6.1
- https://github.com/docker-library/logstash/commit/16ffef2: Update to 6.8.7

kibana:
- https://github.com/docker-library/kibana/commit/c0ffb14: Update to 7.6.1
- https://github.com/docker-library/kibana/commit/3536799: Update to 6.8.7

library/elasticsearch

@@ -4,10 +4,10 @@ Maintainers: Tianon Gravi <[email protected]> (@tianon),
              Joseph Ferguson <[email protected]> (@yosifkit)
 GitRepo: https://github.com/docker-library/elasticsearch.git
 
-Tags: 7.6.0
-GitCommit: 3ee0cc9aaf25ebb7fba9e9e1c8f4f94b77f85366
+Tags: 7.6.1
+GitCommit: 6f143ea97464bbc7c848cf14403efad568b08e67
 Directory: 7
 
-Tags: 6.8.6
-GitCommit: 4c04ee848e9183d70c6109e9325d6a40520d334d
+Tags: 6.8.7
+GitCommit: aafce2f970e14dcbc782761a4ddf4b56a997939e
 Directory: 6

library/kibana

@@ -4,10 +4,10 @@ Maintainers: Tianon Gravi <[email protected]> (@tianon),
              Joseph Ferguson <[email protected]> (@yosifkit)
 GitRepo: https://github.com/docker-library/kibana.git
 
-Tags: 7.6.0
-GitCommit: bd52317f514e1f50d5e8aed9dd581fad7e0648dc
+Tags: 7.6.1
+GitCommit: c0ffb14efc60264a76cff7413f93f261a8352f18
 Directory: 7
 
-Tags: 6.8.6
-GitCommit: 581e38e19e48fcae9ef2bf58afb20ffebe9da082
+Tags: 6.8.7
+GitCommit: 353679916e672ab24a8b75342a18be96bf32d1ae
 Directory: 6

library/logstash

@@ -4,10 +4,10 @@ Maintainers: Tianon Gravi <[email protected]> (@tianon),
              Joseph Ferguson <[email protected]> (@yosifkit)
 GitRepo: https://github.com/docker-library/logstash.git
 
-Tags: 7.6.0
-GitCommit: 52b9ddbb9258a932b37c3152fc9dc74c57274429
+Tags: 7.6.1
+GitCommit: 1bd7995602e94f42da8a650f7330056fd1c2cae8
 Directory: 7
 
-Tags: 6.8.6
-GitCommit: befe697aacab90fc508ae0db4e292dae66a1820c
+Tags: 6.8.7
+GitCommit: 16ffef2618cc8407b7f482937395da8a0553740d
 Directory: 6