feat(tests): Improve test setup for better isolation

This commit enhances the setup process of our tests to ensure they run in a more isolated environment. This is achieved by changing the current directory to the one containing the test file before executing it.

Changes:
- In `gsht.bats`, added a command to change the current directory to that of the test file.
- Also in `gsht.bats`, moved gsht.sh execution into a subshell to prevent side effects on the global environment.
- In `input.bats`, added similar code to change working directory, ensuring all tests run from their respective directories.

tests/gsht.bats

@@ -1,7 +1,10 @@
 #!/usr/bin/env bats
 
 setup_file() {
+    cd "$(dirname "$BATS_TEST_FILENAME")" || exit
+
     (cd ../src && ./gsht.sh gsht.sh --output "$BATS_RUN_TMPDIR/gsht")
+
     chmod +x "$BATS_RUN_TMPDIR/gsht"
 }
 

tests/input.bats

@@ -1,5 +1,9 @@
 #!/usr/bin/env bats
 
+setup_file() {
+    cd "$(dirname "$BATS_TEST_FILENAME")" || exit
+}
+
 input() {
   source ../src/input.sh "$@"