fix: format -> fmt

All of the Charmed HPC tox instances use `fmt`, not `format`. Switching
back to `fmt` to that devx is consistent across Charmed HPC repos.

Misc. changes:

- Add periods to the end of each environment description.

Signed-off-by: Jason C. Nucciarone <[email protected]>

tox.ini

@@ -4,7 +4,7 @@
 [tox]
 no_package = True
 skip_missing_interpreters = True
-env_list = format, lint, static, unit
+env_list = fmt, lint, static, unit
 min_version = 4.0.0
 
 [vars]
@@ -23,8 +23,8 @@ pass_env =
     CHARM_BUILD_DIR
     MODEL_SETTINGS
 
-[testenv:format]
-description = Apply coding style standards to code
+[testenv:fmt]
+description = Apply coding style standards to code.
 deps =
     black
     ruff
@@ -33,7 +33,7 @@ commands =
     ruff check --fix {[vars]all_path}
 
 [testenv:lint]
-description = Check code against coding style standards
+description = Check code against coding style standards.
 deps =
     black
     ruff
@@ -47,7 +47,7 @@ commands =
     black --check --diff {[vars]all_path}
 
 [testenv:unit]
-description = Run unit tests
+description = Run unit tests.
 deps =
     -r {tox_root}/dev-requirements.txt
     -r {tox_root}/requirements.txt
@@ -62,15 +62,15 @@ commands =
     coverage report
 
 [testenv:static]
-description = Run static type checks
+description = Run static type checks.
 deps =
     pyright
     -r {tox_root}/requirements.txt
 commands =
     pyright {posargs}
 
 [testenv:integration]
-description = Run integration tests
+description = Run integration tests.
 allowlist_externals = gambol
 commands =
     gambol -v run tests/integration/test_hpc_libs.yaml