Copyrights not detected if year is missing from (c) or Copyright declaration

### Description

It looks like Scancode fails to recognize a copyright statement if the year as well as the `(c)`, or `Copyright` is not included in the declaration.

Examples of declaration not found by scancode:

```
Copyright The OpenTelemetry Authors
```

```
(c) The OpenTelementry Authors
```

### How To Reproduce

1. Download either:
- https://github.com/open-telemetry/opentelemetry-go-contrib/blob/main/version.go
- https://github.com/containerd/errdefs/blob/main/errors.go
2. Then run to scan:
```
./scancode --json-pp - -c version.go
```
or
```
./scancode --json-pp - -c errors.go
```

And no copyrights are detected in these files.

### System configuration

* What OS are you running on? (Windows/MacOS/Linux)

Linux

* What version of scancode-toolkit was used to generate the scan file?

32.5.0

* What installation method was used to install/run scancode? (pip/source download/other)

source download