Update minimum solc version in all contracts (#3203)

* specify solc not /usr/bin/solc

Signed-off-by: Sally MacFarlane <sally.macfarlane@consensys.net>

* updated pragma. need at least 0.7.0

Signed-off-by: Sally MacFarlane <sally.macfarlane@consensys.net>

Co-authored-by: mark-terry <36909937+mark-terry@users.noreply.github.com>

acceptance-tests/tests/contracts/CrossContractReader.sol

@@ -9,8 +9,10 @@
  * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
  * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
  * specific language governing permissions and limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
  */
-pragma solidity >=0.4.0 <0.9.0;
+pragma solidity >=0.7.0 <0.9.0;
 
 import "./EventEmitter.sol";
 

acceptance-tests/tests/contracts/EventEmitter.sol

@@ -12,8 +12,7 @@
  *
  * SPDX-License-Identifier: Apache-2.0
  */
-
-pragma solidity >=0.4.0 <0.9.0;
+pragma solidity >=0.7.0 <0.9.0;
 
 // compile with:
 // solc EventEmitter.sol --bin --abi --optimize --overwrite -o .

acceptance-tests/tests/contracts/RemoteSimpleStorage.sol

@@ -12,7 +12,7 @@
  *
  * SPDX-License-Identifier: Apache-2.0
  */
-pragma solidity >=0.4.0 <0.9.0;
+pragma solidity >=0.7.0 <0.9.0;
 
 import "./SimpleStorage.sol";
 

acceptance-tests/tests/contracts/RevertReason.sol

@@ -9,8 +9,10 @@
  * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
  * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
  * specific language governing permissions and limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
  */
-pragma solidity >=0.4.0 <0.9.0;
+pragma solidity >=0.7.0 <0.9.0;
 
 // compile with:
 // solc RevertReason.sol --bin --abi --optimize --overwrite -o .

acceptance-tests/tests/contracts/SimpleStorage.sol

@@ -12,8 +12,7 @@
  *
  * SPDX-License-Identifier: Apache-2.0
  */
-
-pragma solidity >=0.4.0 <0.9.0;
+pragma solidity >=0.7.0 <0.9.0;
 
 // compile with:
 // solc SimpleStorage.sol --bin --abi --optimize --overwrite -o .