tar_filter: recognize .tar.zst as zstd (#7093)

tar_filter: recognize .tar.zst as zstd

src/borg/archiver/tar_cmds.py

@@ -42,7 +42,7 @@ def get_tar_filter(fname, decompress):
         filter = "xz -d" if decompress else "xz"
     elif fname.endswith((".tar.lz4",)):
         filter = "lz4 -d" if decompress else "lz4"
-    elif fname.endswith((".tar.zstd",)):
+    elif fname.endswith((".tar.zstd", ".tar.zst")):
         filter = "zstd -d" if decompress else "zstd"
     else:
         filter = None
@@ -349,7 +349,7 @@ class TarMixIn:
         - .tar.gz or .tgz: gzip
         - .tar.bz2 or .tbz: bzip2
         - .tar.xz or .txz: xz
-        - .tar.zstd: zstd
+        - .tar.zstd or .tar.zst: zstd
         - .tar.lz4: lz4
 
         Alternatively, a ``--tar-filter`` program may be explicitly specified. It should
@@ -424,7 +424,7 @@ class TarMixIn:
         - .tar.gz or .tgz: gzip -d
         - .tar.bz2 or .tbz: bzip2 -d
         - .tar.xz or .txz: xz -d
-        - .tar.zstd: zstd -d
+        - .tar.zstd or .tar.zst: zstd -d
         - .tar.lz4: lz4 -d
 
         Alternatively, a --tar-filter program may be explicitly specified. It should