Fix plugin tags that have system twice

Author: rod7760

pyinfra-metadata.toml

@@ -495,13 +495,13 @@ tags = ["system"]
 name = "server"
 path = "src/pyinfra/facts/server.py"
 type = "fact"
-tags = ["system", "system"]
+tags = ["system"]
 
 [pyinfra.plugins."hardware-facts"]
 name = "hardware"
 path = "src/pyinfra/facts/hardware.py"
 type = "fact"
-tags = ["system", "system"]
+tags = ["system"]
 
 [pyinfra.plugins."files-ops"]
 name = "files"
@@ -513,7 +513,7 @@ tags = ["system"]
 name = "files"
 path = "src/pyinfra/facts/files.py"
 type = "fact"
-tags = ["system", "system"]
+tags = ["system"]
 
 [pyinfra.plugins."crontab-ops"]
 name = "crontab"
@@ -525,7 +525,7 @@ tags = ["system"]
 name = "crontab"
 path = "src/pyinfra/facts/crontab.py"
 type = "fact"
-tags = ["system", "system"]
+tags = ["system"]
 
 [pyinfra.plugins."deb-facts"]
 name = "deb"