fix(templates): ensure to use python3 and pip3 (#3170)

src/bentoml/_internal/bento/build_config.py

@@ -527,28 +527,28 @@ def write_to_bento(self, bento_fs: FS, build_ctx: str) -> None:
 # Install python packages, prefer installing the requirements.lock.txt file if it exist
 if [ -f "$REQUIREMENTS_LOCK" ]; then
     echo "Installing pip packages from 'requirements.lock.txt'.."
-    pip install -r "$REQUIREMENTS_LOCK" "${PIP_ARGS[@]}"
+    pip3 install -r "$REQUIREMENTS_LOCK" "${PIP_ARGS[@]}"
 else
     if [ -f "$REQUIREMENTS_TXT" ]; then
         echo "Installing pip packages from 'requirements.txt'.."
-        pip install -r "$REQUIREMENTS_TXT" "${PIP_ARGS[@]}"
+        pip3 install -r "$REQUIREMENTS_TXT" "${PIP_ARGS[@]}"
     fi
 fi
 
 # Install user-provided wheels
 if [ -d "$WHEELS_DIR" ]; then
     echo "Installing wheels packaged in Bento.."
-    pip install "$WHEELS_DIR"/*.whl "${PIP_ARGS[@]}"
+    pip3 install "$WHEELS_DIR"/*.whl "${PIP_ARGS[@]}"
 fi
 
 # Install the BentoML from PyPI if it's not already installed
-if python -c "import bentoml" &> /dev/null; then
-    existing_bentoml_version=$(python -c "import bentoml; print(bentoml.__version__)")
+if python3 -c "import bentoml" &> /dev/null; then
+    existing_bentoml_version=$(python3 -c "import bentoml; print(bentoml.__version__)")
     if [ "$existing_bentoml_version" != "$BENTOML_VERSION" ]; then
         echo "WARNING: using BentoML version ${existing_bentoml_version}"
     fi
 else
-    pip install bentoml=="$BENTOML_VERSION"
+    pip3 install bentoml=="$BENTOML_VERSION"
 fi
 """
             )