feat(input): use the config file from given path

fixtures/cliff.toml

@@ -0,0 +1,25 @@
+# configuration file for git-cliff (0.1.0)
+
+[changelog]
+header = "# Changelog\n"
+body = """
+{% if version %}\
+    ## [{{ version | replace(from="v", to="") }}] - {{ timestamp | date(format="%Y-%m-%d") }}
+{% else %}\
+    ## [unreleased]
+{% endif %}\
+{% for group, commits in commits | group_by(attribute="group") %}
+    ### {{ group | upper_first }}
+    {% for group, commits in commits | group_by(attribute="scope") %}\
+        #### {{ group }}\
+        {% for commit in commits %}
+            - {{ commit.message | upper_first }}\
+        {% endfor %}
+    {% endfor %}\
+{% endfor %}\n
+"""
+trim=true
+footer = "<!-- generated by git-cliff -->\n"
+
+[git]
+conventional_commits = true