Make QVM notebooks use development version of cirq_google (#7439)

Problem: QVM notebooks would use the last stable cirq_google
if imported before package upgrade.

Solution: Import cirq_google only after its possible upgrade.

Fixes b/425769714

Author: pavoljuhas

docs/hardware/qubit_picking.ipynb

@@ -95,8 +95,9 @@
     "try:\n",
     "    import cirq\n",
     "\n",
-    "    # trigger ImportError when cirq is not cirq~=1.0.dev\n",
-    "    from cirq_google.engine import load_device_noise_properties as _\n",
+    "    # raise ImportError when cirq is not new enough\n",
+    "    if cirq.__version__ == \"1.5.0\":\n",
+    "        raise ImportError(\"This notebook requires the development version of Cirq\")\n",
     "except ImportError:\n",
     "    print(\"installing cirq...\")\n",
     "    !pip install --upgrade --quiet cirq~=1.0.dev\n",

docs/simulate/noisy_simulation.ipynb

@@ -84,8 +84,9 @@
     "try:\n",
     "    import cirq\n",
     "\n",
-    "    # trigger ImportError when cirq is not cirq~=1.0.dev\n",
-    "    from cirq_google.engine import load_device_noise_properties as _\n",
+    "    # raise ImportError when cirq is not new enough\n",
+    "    if cirq.__version__ == \"1.5.0\":\n",
+    "        raise ImportError(\"This notebook requires the development version of Cirq\")\n",
     "except ImportError:\n",
     "    print(\"installing cirq...\")\n",
     "    !pip install --upgrade --quiet cirq~=1.0.dev\n",

docs/simulate/quantum_virtual_machine.ipynb

@@ -97,10 +97,12 @@
     "\n",
     "try:\n",
     "    import cirq\n",
-    "    import cirq_google\n",
     "\n",
-    "    # trigger ImportError when cirq is not cirq~=1.0.dev\n",
-    "    from cirq_google.engine import load_device_noise_properties as _\n",
+    "    # raise ImportError when cirq is not new enough\n",
+    "    if cirq.__version__ == \"1.5.0\":\n",
+    "        raise ImportError(\"This notebook requires the development version of Cirq\")\n",
+    "\n",
+    "    import cirq_google\n",
     "except ImportError:\n",
     "    print(\"installing cirq...\")\n",
     "    !pip install --upgrade --quiet cirq-google~=1.0.dev\n",

docs/simulate/qvm_basic_example.ipynb

@@ -104,10 +104,12 @@
     "\n",
     "try:\n",
     "    import cirq\n",
-    "    import cirq_google\n",
     "\n",
-    "    # trigger ImportError when cirq is not cirq~=1.0.dev\n",
-    "    from cirq_google.engine import load_device_noise_properties as _\n",
+    "    # raise ImportError when cirq is not new enough\n",
+    "    if cirq.__version__ == \"1.5.0\":\n",
+    "        raise ImportError(\"This notebook requires the development version of Cirq\")\n",
+    "\n",
+    "    import cirq_google\n",
     "except ImportError:\n",
     "    print(\"installing cirq...\")\n",
     "    !pip install --upgrade --quiet cirq-google~=1.0.dev\n",